In just the first few minutes, you had highlighted enough of Kashgar for me to want to play it. In fact, I was preparing to watch your whole vid when I got a spare hour, in preparation for playing it in German on yucata; but it looks like there's an English version of it online. So if your goal was to get people into new games: mission completed, my good man!
1.) that I have not many games, especially not new ones as I mainly play with my wife and we can't afford to buy always the newest games...
and 3.) that my games are in German and I want to make videos in English.
How related are these two points? I mean, do you
only have old German games for which an English translation doesn't exist?
That still might be mildly entertaining. But if the games exist in English in some form, don't let that stop you.
2.) I don't have a good camera only my smartphone (I mean rahdo started with his iPhone as well, but I'm not sure if I could do that)
Don't let that stop you, either. You already admitted that rahdo started that way, so the only thing holding you back is you. Of course, this online recording thing seems to be working pretty well, too...
I can't necessarily explain why rahdo's vids are so popular, but for me personally, the general style of his presentation is key. He gives us all the information we need. He doesn't bang on about (too much) unrelated stuff. He keeps his run-time relatively short. LP's are a different bag than reviews, obviously, but keep those points in mind anyway.