Did you know that in most cases, you only need to bypass whatever method is used for checking your location. The server that does this, is usually not the one you stream your video from. It means that after passing the location check, you can actually connect directly to the video server for watching the video itself (and suffer much less from connectivity issues, if at all).
Look at this trick for example.
"Basically we are interested in proxying content only for certain domains. The actual streaming media sits on CDN networks and is usually not geo-locked. The amount of proxying we'll end up doing will be relatively insignificant compared to a VPN-based setup."
In case you want to try it out, there is a free service that does it. I'm a customer of a paid one which combines both VPN ("ibVPN") and DNS ("ibDNS") based services. On the paid front there are many other services that offer similar functionality. Most offer several hours of free trial, so you could see which ones works best for you.
Having said that, did you try contacting your ISP for support? Perhaps they change something in their routing tables which happens to work very bad for you? Maybe they can help.