Ugg... that's ugly and a problem. That could definitely result in slow speeds and problems streaming videos.
Could be signal related issues (especially upstream signal quality degradation) or bandwidth congestion.
I'd lean toward signal issues first since it's a much more common issue.
Best bet would be to get a hold of tech support and ask about upstream
SNR, MER, and/or errors. Maybe try the Direct forum here.--
If it's important, back it up... twice. Even 99.999% availability isn't enough sometimes.