I teach a lot of beginners and find that one of the most common problems they encounter is playing with too much tension, whereby they use more effort than is required to fret notes and chords.
Sometimes it can be the fault of the guitar itself, because the action is too high (the distance of the strings from the fretboard), and this is a common problem with cheaper guitars, particularly steel string acoustics. If you think this is an issue it could be money well spent paying for a professional set up, and requesting that they lower the action. Usually music shops will provide this service for a reasonable price. You can do it yourself but I don't want to recommend that people start butchering their instruments!
I'm going to assume that your guitar is in good working order for this lesson. The video shows you how to play a simple chromatic exercise which after a bit of practice you should find quite easy. The main benefit of using this exercise regularly is that it will train your hand to fret notes in a more comfortable way. It can feel unnatural to bend your fretting hand wrist and use all 4 fingers on the fretboard, but this is often what is required to play riffs, chords and lead solos.
Because it feels unnatural to hold this shape with your fretting hand, it is common for beginners to use a lot of effort to play, and create a lot of tension in the process. Hopefully some of the troubleshooting tips will help you to avoid this common problem, and make playing feel easier and more enjoyable.
I don't think it matters whether you want to play like Noel Gallagher or Paul Gilbert, developing good fretting technique will help you to learn more effectively. Have fun!