made the PlayVideoActivity return to its VideoItemDetailActivity when the back button is pressed, by setting its parent activity in the manifest. Also grammar fixes for existing comments

app/src/main/AndroidManifest.xml

@@ -68,6 +68,7 @@
         <activity android:name=".PlayVideoActivity"
             android:configChanges="orientation|keyboardHidden|screenSize"
             android:theme="@style/FullscreenTheme"
+            android:parentActivityName=".VideoItemDetailActivity"
             >
         </activity>
         <activity

app/src/main/java/org/schabi/newpipe/StreamingService.java

@@ -24,9 +24,9 @@ public interface StreamingService {
     class ServiceInfo {
         public String name = "";
     }
-    public ServiceInfo getServiceInfo();
-    public Extractor getExtractorInstance();
-    public SearchEngine getSearchEngineInstance();
+    ServiceInfo getServiceInfo();
+    Extractor getExtractorInstance();
+    SearchEngine getSearchEngineInstance();
 
     /**When a VIEW_ACTION is caught this function will test if the url delivered within the calling
     Intent was meant to be watched with this Service.

app/src/main/java/org/schabi/newpipe/VideoItemDetailActivity.java

@@ -69,7 +69,7 @@ public class VideoItemDetailActivity extends AppCompatActivity {
                         arguments.putInt(VideoItemDetailFragment.STREAMING_SERVICE, i);
                         try {
                             currentStreamingService = i;
-                            extractor = (Extractor) ServiceList.getService(i)
+                            extractor = ServiceList.getService(i)
                                     .getExtractorInstance();
                         } catch (Exception e) {
                             e.printStackTrace();

app/src/main/java/org/schabi/newpipe/VideoItemListFragment.java

@@ -172,7 +172,8 @@ public class VideoItemListFragment extends ListFragment {
     private void startSearch(String query, int page) {
         currentRequestId++;
         terminateThreads();
-        searchRunnable = new SearchRunnable(streamingService.getSearchEngineInstance(), query, page, currentRequestId);
+        searchRunnable = new SearchRunnable(streamingService.getSearchEngineInstance(),
+                                            query, page, currentRequestId);
         searchThread = new Thread(searchRunnable);
         searchThread.start();
     }
@@ -227,10 +228,6 @@ public class VideoItemListFragment extends ListFragment {
         }
     }
 
-    void displayList() {
-
-    }
-
     /**
      * The serialization (saved instance state) Bundle key representing the
      * activated item position. Only used on tablets.

app/src/main/java/org/schabi/newpipe/youtube/YoutubeExtractor.java

@@ -199,7 +199,7 @@ public class YoutubeExtractor implements Extractor {
                 videoInfo.audioStreams = parseDashManifest(dashManifest, decryptionCode);
             } catch (Exception e) {
                 //todo: check if the following statement is true
-                Log.e(TAG, "Dash manifest seems not to bee available.");
+                Log.e(TAG, "Dash manifest doesn't seem to be available.");
                 e.printStackTrace();
             }
 

app/src/main/java/org/schabi/newpipe/youtube/YoutubeSearchEngine.java

@@ -57,14 +57,14 @@ public class YoutubeSearchEngine implements SearchEngine {
         int i = 0;
         for(Element item : list.children()) {
             i++;
-            /* First we need to determine witch kind of item we are working with.
-               Youtube depicts fife different kinds if items at its search result page. These are
-               regular videos, playlists, channels, two types of video suggestions, and a no video
-               found item. Since we only want videos, we net to filter out all the others.
+            /* First we need to determine which kind of item we are working with.
+               Youtube depicts five different kinds of items on its search result page. These are
+               regular videos, playlists, channels, two types of video suggestions, and a "no video
+               found" item. Since we only want videos, we need to filter out all the others.
                An example for this can be seen here:
                https://www.youtube.com/results?search_query=asdf&page=1
 
-               We already applied a filter to the url, so we don't need to care about channels, and
+               We already applied a filter to the url, so we don't need to care about channels and
                playlists now.
             */
 
@@ -102,9 +102,9 @@ public class YoutubeSearchEngine implements SearchEngine {
                 Element te = item.select("div[class=\"yt-thumb video-thumb\"]").first()
                         .select("img").first();
                 resultItem.thumbnail_url = te.attr("abs:src");
-                // Sometimes youtube sends links to gif files witch somehow seam to not exist
+                // Sometimes youtube sends links to gif files which somehow seem to not exist
                 // anymore. Items with such gif also offer a secondary image source. So we are going
-                // to use that if we caught such an item.
+                // to use that if we've caught such an item.
                 if(resultItem.thumbnail_url.contains(".gif")) {
                     resultItem.thumbnail_url = te.attr("abs:data-thumb");
                 }
@@ -113,7 +113,6 @@ public class YoutubeSearchEngine implements SearchEngine {
                 Log.e(TAG, "GREAT FUCKING ERROR");
             }
         }
-
         return result;
     }
 }

app/src/main/java/org/schabi/newpipe/youtube/YoutubeService.java

@@ -34,11 +34,11 @@ public class YoutubeService implements StreamingService {
     }
     @Override
     public Extractor getExtractorInstance() {
-        return (Extractor) new YoutubeExtractor();
+        return new YoutubeExtractor();
     }
     @Override
     public SearchEngine getSearchEngineInstance() {
-        return (SearchEngine) new YoutubeSearchEngine();
+        return new YoutubeSearchEngine();
     }
     @Override
     public boolean acceptUrl(String videoUrl) {