are good, with exception for one thing; he teaches the use of 'hollows'.This should really be avoided, it is the work of t3h d3vil!
What hollow does is basically to generate a hollow section of selected brushes, but it fails to understand where to split, in order to minimize vertices.
If you get a high vertice count, your map will require a more powerful system in order to draw decent, playable framerates for the players.
I made a screenshot of a basic cube (room) with 'hollow' and how different it is from an optimized section, even though you cannot see the difference on the finished result, the Quake III engine can.
It might not matter in a small, enclosed, 1v1 tournament map without walls, but make something with a bit of size and you'll notice the difference at once.
Learn it the right way, it will save you from lots of headache in the long run.