Yxflash for iphone problem

[websnake0]

i wanted to play xvid files on my iphone but when i launch Yxflash it gives me a
black screen for half second and then i find my self returned to iphone app selection screen.

i tried 3.1.8 and 3.1.9 both version but both keep crashing.
i installed them using ifile.

i am using iphone form 2 days i am new in iphone scene so i don't know a lot (newbie) this is my 2nd day.

i am using...
iphone 3gs 16gig
firmware - 3.1.3 (jailbroken)