Nice vid! And on the topic of not knowing what to say, just be yourself! It's especially hard to commentate in parkour because your not doing much. You can see that in my video lol. Usually the big YouTubers have dry commentary as well in parkour so don't fear! Another thing to try is recording with other people, it makes the commentary seem more natural and it just flows like you see in mine and Nate's vids when we play together. The commentary just flows instead of having a lack of what to say. But it will come in due time of practice and trial and error! Just keep at it! You already have great content and I can't wait to see more!