There is no easy answer.

It depends on a number of factors, what te video's for, how long the track is, which track it is etc.etc.

The Performing Rghts Society http://www.prs.co.uk/ are responsible for collecting the fees and work with the Mechanical Copyright Protection Society http://www.mcps.co.uk/ but organisations such as the Institute of Videographers http://www.iov.co.uk/ and the Guild of Videographers http://www.gpv4u.co.uk/ have schemes to arrange payment.

It's best that you contact them as you know what you want and what you'll use it for.

Don't listen to any saloon-bar lawyers on this subject, there are all sorts of urban myths about copyright and it can cost you a lot of money if you don't do it right.