Support start= timestamps for YouTube

Author: wb9688

extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubeStreamExtractor.java

@@ -240,7 +240,7 @@ public long getLength() throws ParsingException {
      */
     @Override
     public long getTimeStamp() throws ParsingException {
-        return getTimestampSeconds("((#|&|\\?)t=\\d{0,3}h?\\d{0,3}m?\\d{1,3}s?)");
+        return getTimestampSeconds("((#|&|\\?)(t|start)=\\d{0,3}h?\\d{0,3}m?\\d{1,3}s?)");
     }
 
     @Override

extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/stream/YoutubeStreamExtractorAgeRestrictedTest.java

@@ -48,6 +48,8 @@ public void testGetInvalidTimeStamp() throws ParsingException {
     public void testGetValidTimeStamp() throws IOException, ExtractionException {
         StreamExtractor extractor = YouTube.getStreamExtractor("https://youtu.be/FmG385_uUys?t=174");
         assertEquals(extractor.getTimeStamp() + "", "174");
+        extractor = YouTube.getStreamExtractor("https://youtube.com/embed/FmG385_uUys?start=174");
+        assertEquals(extractor.getTimeStamp() + "", "174");
     }
 
     @Test