Where are you based? Here in the UK, video production companies sign up to the Mechanical Copyright Protection Society (MCPS). Then we can access all of the music libraries with material written purely for corporate videos, TV and radio commercials, online and so on. Once you've used library music in a production, you declare how much you've used to the MCPS, and they issue a licence for the usage. Rates are very much cheaper than using commercial tracks - for example, to use 30" of music in a corporate (non-broadcast) production would cost around £35. It all depends where you are (I'm pretty sure the US has a similar organisation to the MCPS here in the UK), and if you're producing videos professionally.