Control-click the top of the column of the download window & choose to show Vendor/Version. This will show which gnutella client program you're downlding from. If it's RAZA (Shareaza) then that might be why you're having problems. They are reknown for being difficult to connect with, slow speed offerings, etc. This is because they use multiple networks which require they upload as fast as they download so thus, there's not much left over for gnutella. Raza users do tend to have the most videos however.

Get into using Bitzi, & if you haven't seen it already, see Movie download issues

Downlding such large files whilst using dial up is a big ask. Whilst I used dial up, I never or rarely downlded files larger than 200 MB. Dial up only offers a max of about 5-7 KB/s upload & downld combined. If you want to keep downlding lots of videos, perhaps consider upgrading your connection to something like broadband for example.