Why do movies seem to take long to load onto my PlayBook?

I've done it before, most trial-and-error. The problem is that my PC does not acknowledge that the PB is connected, although the PB says it is, and the Desktop Manager wants to sync.

I tried to do it wirelessly, as suggested here but I don't know why one movie will take 9 hours up to 1 day when the previous suggestion says it should take about 15 minutes.

I tried downloading the newest Desktop Manger but it failed twice.

This is really frustrating. I'd be humble enough to admit that I'm the *****, but I need someone to prove that first. How do I simply move a video from my desktop to my PlayBook?!!
Thanks

The video needs to be in .MP3 or .MP4 format, for the PB to recognize it.... I believe