I have been tracking my upload speeds on numerous stock footage sites over the past two months as I have uploaded over nearly 2000 clips between them. I have Cox high speed Internet business plan with 16 mbit download and 8 mbit upload speeds. I specifically got that plan for the faster upload speed.
Pond5 - 350 KB/s average
Can Stock - 145 KB/s average
RevoStock - 122 KB/s average
StockXpert - 120 KB/s average
ShutterStock - 103 KB/s average
Fotolia - 98 KB/s average
Dreamstime (photos only, not footage) - 91 KB/s average