GOOGLE is your answer for all of these options
In short:
- deinterlace removes interlacing, odd/even lines of video are switched between each other 25times in one second(for 25fps), deinterlace will calculate missing lines so you see 25 full pictures in a second = higher quality and smoother playback. But loss of quality if video is progressive and not interlaced

- A/V sync alternative as Joksi said tries with another method to sync audio with video
- force subs is self-explaining
- skip loop filter deblocking - if you have dual core, disable(=don't skip) it for better video quality(only relevant for H264 HD video)
- keyint=5;vqscale=3;vqmin=5 ==> try google what these parameters do in mencoder
- force fps parsed from ffmpeg in the meta file - self-explaining, will force fps which detects ffmpeg. Some videos have no fps info in header or it is faked (when audio is 25fps and video 23.976), so ffmpeg info is used. Sometimes it will fix synchonization or data not supported but in many cases it have no effect at all.[/quote]
very weird that we are on a db about PMS and i get a response that google is where i should find my answers. I know i can look there but this stuff to me is VERY CONFUSING, SO WHY NOT GO TO THE SOURCE OF PEOPLE WHO ALREADY KNOW HOW TO DO THIS STUFF?
I only ask these questions here due to the fact that you guys (most of you) already understand this stuff and ,ight be able to give us an answer in laymans terms in the DB made for the program we are all using.
Thanks for the knowledge you have helpt me obtain... everything you have said is great info for someone who gets easialy confused with all this stuff.