I've only ever uploaded 1 10min video to utube so not much experience with these issues....i've suspected my isp throttles the download speed as its much quicker after midnight and i dont think its because there are less people online then ...so could be something similar for uploading too...

but if they limit upload speeds from 7 - 56kb emails would take ages to send too? unless the size of the file being uploaded triggers the throttling.... also a large file is more susceptible to corruption if its only able to send tiny data packets at a time...

but anyway im babbling! Good luck we're all counting on you! :)