Rainbowzz - thank you so much for explaining it in a way that I felt I actually understood for the first time ever!

Sky - I do have AVG running constantly - so that might be a factor too.

Thanks so much.

There have been a few things I have wanted to watch that I have let buffer whilst I am busy with other things. After about a half hour or so - I can usually watch it. Even if it is only a 2 or 3 minute video.

I will contact my ISP though - I think they should shed more light, even if just on principle.