I'll give some feedback. Yea I can say it's all great and good but I don't think that's very helpful. But here's some points I can give that I think you can improve on.
Layout. You have playlist, fine. But if you lay them horizontally with the first 3-4 videos showing and clickable, it might encourage people to click on one of them. If you have 10-12 different vids available instead of 3 playlists, that might help.
Thumbnails. Drop the bleeding horror font and have something sharper that's easy to read on the smallest screen. Try taking an iPhone 4 and seeing what's readable. I had this problem too, but have a friend test read everything on the smallest device and see if she can actually read it all. Doing it yourself you can be a little biased because you made it, you know what it says and your brain has already clicked with what it's supposed to be, fresh eyes have not. Don't have much action going on in the bottom right corner as the video runtime will cover it up.
I'm checking your channel on an iPad and the trailer doesn't automatically play but shows the thumbnail. It only shows the middle third. So any text on the top or bottom third get cut off as well. You do use a stroke of an opposite color to make text stand out, so that's very good.
Descriptions. The videos themselves are fine, you get to the point and it's good but there's no way they'll ever be searched because the title and description is way too short. For example "DIY felt phonecase" only gives google 3 words to find that video. A longer title like "How to make an awesome do it yourself / DIY felt fabric case for your iPhone, or android phone" would have a better chance as it has many words that are searched often. The description of the video also does not have the word "DIY" !! But having the same word in title and description will help boost it in the search engine. It's not. Only YouTube , but google that also can be used for finding videos and so every bit helps.
I can't see your tags but I can imagine they are your name, diy, fabric and phone case, which won't work. Long strings like "diy fabric cases for iPhone" "do it yourself iPhone case" will work better as that's likely what people will type if they are looking for this. Typing diy only into YouTube or google will get too varied of results that they aren't helpful.
Fill up 490-500 characters with tags, 90-100 in the title and 4500-5000 in the descriptions. The links you have and the layout are fine though, just give it more!