More improvement for mpeg pts.

The mpeglastTimeStamp is probably wrong in some videos. So a video is
end only if there is no more data for decoding.
Btw, based on my tests, it seems most games already know when the video is end, and they would end videos when the video end has reached and no needs for any error returns. So in most of time, we should not get "video end reach" info logs, and videos would end by themselves.