file types with youtube

[Dennis]

hey listers. i am trying to upload some video files to youtube and they 
will only play for 54 seconds. they are different lengths but all the 
same file type. they were recorded with my ipad and i converted them to 
wmv. does anyone know if there is a file type that is only for youtube 
or is it the size that matters. i'm frustrated with this because i've 
wasted the last 2 evenings wrestling with this. thanks for any help.