Interesting that this thread got revived at some point.
I can tell you guys a bit more about what I found out myself. At one point I pretty much figured out the entire mechanism behind it, it's very unusual (at least to what I'm used to).
Unfortunately this is quite some time ago and I'm unsure if I still have any of my documents to this. In the end it turned out that this strip is useless for anyone who want's to address single LEDs fast.
There is one command that just shifts in a new color from the left but there's no latch, so the shift is done at once. The frequency you can do that with is not satisfying since when you go to the max (which I belive was something like 30 Hz for 5m) you get weird artifacts due to the missing latch. Also you cannot shift any color, but only red, green or blue or any on/off combination of those (yellow, white, etc.).
To get PWM you have to send another command where you make the strip mix all of it's current colors with the neighbouring color to the right or the left. And there's some other stuff, mixing segments of the strip etc.
If anyone is seriously interested, I can look for the documents, I might still have them on another PC.
In general I got to the conclusion that this strip is absolutely useless for anything else than what the controller that comes with it does. So if you just wanna light your room this one might be for you, but if you want to address each LED to display something then you should go for a different strip, which is also what I did.
My strip now serves as a remote controlled ceiling light for a friends living room.
PS:
There's no data/clock line. It's more like two intermixed serial lines with varying bit times within the single bits. And also command and value bits are mixed. It's a huge mess.