WTF is with uploading

Every time I try to upload it freezes at about 80 percent for no frickin reason. My files are usually like 100 to 180 mbs at most and the limit is two hundred. But actually when my files are like 80mbs or so they do go through but most of the time they come up in error after the conversion process. And that really gets on my mother frickin nerves. And it makes me even angrier when I see vids on here that are like over an hour long. WTF.

So if anybody who uplaods reads this, pretty pretty please tell me what my problem might be. I'm about to cry : (

I use avs video converter 6 to convert my files to flv because the avi and mkvs and whatever the others are omg I think is one. they're always like uber big. Maybe another format is better??? Help me please I'll love you forever