That looks normal to me, it looks like foam is collecting and condensing the way it should.
I came in today to a cup full of clear water. So far my observations are we have two problems and keep in mind, mine is a prototype made back in September and deviates slightly from what you have so this may not apply but based on Aarons comments I assume it is so.
First, be sure the L is firmly inserted, this is critical, once this is correct I think you will find the problem is a cup full of water and not no skimming at all.
Now, you are at the cup full of water stage and here is where the bigger problem is. As Aaron said the venturi screw doesn't work perfectly. From what I can tell the hole that the screw is supposed to cross is too far back so the screw doesn't close the hole. The screw is standardized so the issue has to be the top plate. For an immediate solution I found that a screw that is the same diameter but slightly longer is included in the installation hardware and will close the hole and give you the range of adjustment you need to get proper skimming. Apparently some people skimmers are fine as delivered as I have gotten a few positive comments. If yours isn't let me know and I can send the screw if necessary for the time being and I will work on getting the new top plates to replace the ones that aren't correct. Unfortunately I couldn't get through to Tunze today, the line was busy every time I tried.