Are you asking "can you get away without closing gop's for standalone playback?" The answer would be yes, since Tmpgenc and CCE uncheck this default anyways, and it's what I run for standalone players. I've never had to check the box for closed GOP's, but can guess that it should be okay. Like I said, I'm sure this helps for someone who plans on video editing the mpeg 2 file(because mpeg is tricky to edit, closed gop's help the encoding software). But it should work also for simple encoding for standalone. Give it a try. Two short tracks, one with, one without closed GOP's. Sorry I couldn't help you any more. I'm just pulling from what I've read on previous posts. Good luck!!!!