Well your video will probably have syncronised itself with the time signal sent along with the teletext pages and with regard to the computer you'll find if you right click on the time on your screen then select adjust time it will have the option to update from the net selected and it a smart cookie anyway it knows all about BST.
all of my electronic equipment that shows the time went back an hour including my windows pc, but very oddly my two macs running os x.2 needed to be turned back manually. somethings are easier on a mac
It's Not Necesarrily truwe that your computer connected to the net Microsoft are clever people and have programmed in the OS that the clocks go back and forward on certain dates and just do it automatically - the adjust time portion is to check with the atomic clock (Which is always right)