In order to be allowed to use a song in a video, you must first request permission from the publisher of that song. Contact details for the publisher can be found in our catalogue.
Once that is done, you obviously want to share your video online as soon as possible. Please keep in mind that when you put something online, this constitutes a communication to the public, for which you will need a licence from Sabam.
Also keep in mind that in addition to the copyright (managed by an authors' society such as Sabam) there are also neighbouring rights (such as the rights of the producer who is responsible for the recording). If you want to make certain videos available on the Internet, the producers must grant you permission beforehand.