Player: Fix video playback for videos that have already been watched.

Trying to watch an already watched video will make the video start 15
seconds before the end of the video. This is not very comfortable when
listening to music or watching/listening playlists over and over.

assets/js/player.js

@@ -351,7 +351,12 @@ if (video_data.params.save_player_pos) {
     const rememberedTime = get_video_time();
     let lastUpdated = 0;
 
-    if(!hasTimeParam) set_seconds_after_start(rememberedTime);
+    if(!hasTimeParam) {
+      if (rememberedTime >= video_data.length_seconds - 20)
+        set_seconds_after_start(0);
+      else
+        set_seconds_after_start(rememberedTime);
+    }
 
     player.on('timeupdate', function () {
         const raw = player.currentTime();