First...
There is no way I will hit the "thanks" button for your post ...
"thanking" you just doesn't seem proper.
Nor would poking (any kind of) fun at your situation be any more appropriate.

Personally I know less about the various (are there many media players for the n900 actually?) media players for the n900 ...compared to the n8x0s ...

Is it the stock media player you are using ...that went "teats up" on you?

(hm. actually ...you probably should start a thread in the n900 subforum under the title
"[name of] media player just stopped playing video. Help!"...
if you can't find a thread that discusses your situation, then start one, someone must have an idea what the issue is..and have dealt with it before...
can't hurt Maemish...
...someone must have gone through the same ...and can point you the right way...
and if anyone takes a poke at you...
ooooh!
I will give them such a pinch.
so cheer up)