Some videos uploaded last year might not be work in google docs preview. You can upload file up to 1 GB that is free, if you want to upload more you can add the storage size by paying nominal charge i.e. 20 GB approx Rs 500 per year.
Supported files format to run the videos in the google docs
MPEG4, 3GPP, MOV, AVI, FLV, WMV, WebM