Virgin are so variable. I've been with them a few years now, and I get more of the up to speed than I did with ADSL - but don't normally test it in the evening (but never noticed serious streaming problems).
I did have a long period where it would drop out a few times each week - often mid morning: noticeable when I was working at home. It got so bad (and customer support were the usual chocolate teapot of usefulness) that I got a VDSL line from someone else and a failover/sharing router - Linksys LRT224. That has worked nicely to smooth out any problems - and as far as I can tell the VDSL has been stable (and quick ~75/19).
More recently (last six months) Virgin finally rolled out the 200Mb service in my area (after years of missed promises) and some initial problem I've checked and I've had one outage of 9 minutes since the end of March on the Virgin line, which I'm not going to complain about for consumer grade product. Don't check the other one but the router says connected for 9 days - so something happened.
I guess because the Virgin network is put together from varying quality bits and pieces they bought from others they are going to vary around the country. [Not apologising for them - they are scum on pricing for existing customers, not rolling out new tech until a competitor gets close, (lack of) customer service, marketing spam etc. etc. - but they are generally predictable scum working with shit infrastructure that customers wont pay to have improved.]