Some tracks are designed to loop with a seamless edit, some are not quite so easy to loop. The ones that loop the most seamlessly normally have no obvious ending, they end somewhat abruptly. With these ones you just bang them up against each other with copy, paste or loop. Other tracks that have a more obvious ending such as a fade out may not loop so easily or naturally. With music like that it is often best to have two audio tracks with crossfades from the first loop to the second loop. You adjust the cross fades to sound natural. I record/write both types of tracks. Both have their place, depending on the vibe or feel you are after in your video.