Share your experience!
Problems that I encountered after the ICS upgrade
1) iTunes video cannot be played using the native video player, previously I can play in Gingerbread
2)Annoying thin white line on the bottom and right hand side when playback of videos
Does anyone encounter such problems? 
are you using stock player ?
and that thin white line , is it visible while playing any video or just that itunes video ?
you may try mx player from the android market \ play store.
Are you using an Xperia Arc S running on ICS?
All videos have this annoying white line. And I don't wish to use a 3rd party app when my phone has no such problem before ICS.
Do you know what format these files are in?
Youtube's Mp4 videos in 1280x720p, self encoded Mp4 in 854x480 (same resolution as ARC display)
I don't have such problem watching the same video file on 3rd party app or even on youtube app.
I think it has to do with the native video app output display on ARC since I don't have such problem when running on gingerbread.
I did a screen capture of what I'm observing when watching the video and I think it has to do with grey background in portrait mode. Added a black border so that you can see that annoying white line.
Could you please reset the phone and set it up again. This can be done the following way:
[Menu] > [Settings] > [Backup & Reset] > [Factory Data Reset].