Wow.. I'll break that up and answer them.
>Can you provide a bit more details?
Yes :-)

>What does it mean "can't play"? Does it simply not start video playback, freezes at start, freezes in the middle of movie, reboots the device or whatever?
Yes, it does all of the above. Sometimes I get a little bit (never more than 5 minutes) into the movie. Sometimes, I just get to the all black screen. If I wait long enough, it sometimes stutters some of the video before dying. Infrequently, I have been able to kill mplayer, but usually it locks up and either reboots, or I pull the battery.

>Do small videos play better?
Yes, although I have similar (same?? not sure) problems when I try to view small (music) videos with ukmp. I usually view those videos with the built in front end for mplayer. Let me disable VM and try ukmp. I never tried to launch the movie with ukmp.
(Removed VM, rebooting.. (I know you wanted a play by play.. :-) )
Seems to work better. The video stuttered when it started, but after about 15 seconds, seemed to play fine in ukmp.
(White-n-Nerdy Weird Al flv file downloaded from utube.)
(Reenabling VM , rebooting- Yes, I know I should have replayed it this way BEFORE I disabled VM.. I was distracted.. :-)
OK, definately worst. umkp launched mplayer but before it went full screen, I heard the start of the video and the main part of the screen (not the side or top) went black. It paused a bit before, but only for a second or two. It's been 40 seconds like that now. OK, 1 minute, now full screen, but no motion or sound. Just the opening frame.
....
over 30 seconds, no movement...
....
I'm thinking I'm locked up.. So, de(... all black screen now...)finately worse. I think it's trying to work, but (..weird colors in the top left 1.5"x1" of the screen..) just going really really slow.
(REBOOT - NOKIA screen - by itself, I didn't do it.)
(I'll play just with mplayer frontend when it comes back.)
Selected video, playing now smooth.
I suppose that the video issue could just be a umkp problem, or related to the amount of memory that ukmp takes up???
Video still playing fine...
(Other difference, ukmp plays the video in full screen. mplayer gives me a 1/4" black border on this video.. )
>Do the problems disappear with virtual memory disabled?
Yes, I was able to watch the whole movie without problems. This is a ripped DVD 2 hour 480Mb file converted with mediaconverter.

>Is the problem always reproducible/often reproducible/occurs rarely?
Yes, with the large movie, it's for sure everytime. With smaller videos, it's a bit trickier. It's not a question of does the 770 lockup/reboot, but rather is there more jerkiness/pausing, and that could be caused by other apps I have run/am running. I don't always reboot before playing small videos. I always rebooted before watching the movie to be safe since I was having problems.

How's that? :-)

desiv
I'm running ITOS2006 3.2006.49-2