Thank you Simon! He didn't really indicate what tempo and his demonstrations are all over the place, but the lesson was called "slow blues" so I just picked a rhythm that I thought was sufficiently slow ๐
WieWaldi would know a little more about how the course proceeds (he is further ahead than I am), but I definitely think that Christian's aim is to teach full autonomy ๐ But for this particular lesson, the improvisation is confined to "hit that note, double it, triple it, and make sure you don't miss your chord changes..." I also think he is working on hand independence and getting across what sounds bluesy and what doesn't, before he lets us loose on the real stuff. But that's just a guess.
I know, I moan a lot, but I really am enjoying the lessons and I'm sure I will get into full improvisation soon enough. I agree that I should probably get a little more adventurous and just do it. Less moaning, more improvising 
Simonb Are you using music there, or playing from memory?
I have the sheet music, but for these lessons I try to learn them as soon as I start the lesson. So playing from memory here.