I have this problem too. I guess there is no workaround yet?
My humble understanding is that there is an issue with hnak's driver used for the Intel NIC, notably the one found on the GA-Z77-xxx motherboards.
We should try to advertise the issue on other relevant threads and forums, short of talking directly with hnak.
I think this is a very significant issue, but I am afraid it may go unnoticed for a long time (well, maybe I am writing this here while this is actively being discussed (solved?) somewhere)
I have had this issue (youTube endlessly loading html5) for quite a while, but I didn't know it was supposed to work, I thought it was a general Mac OS issue that also affected regular Macs. So I was not even trying to troubleshoot the problem.
Many users who do have Flash will not see the problem on YouTube and never worry about it, or understand the problem (easy to dismiss it to a Safari issue). It certainly affects other areas, such as Skype apparently, but here again, it is easy to dismiss it as a shortfall of bandwidth from your ISP for instance.
Personally, I've had frustrating issues with Remote Screen sharing via iChat/Messages that rarely succeed connecting and I am starting to suspect this, although it does also happen when not using that driver, just less frequently. So far, my reaction was "I checked my bandwidth (Down & Up) and it is great, so the issue MUST BE on the other end with their second-rate ISP".
Now that I am becoming aware that large amounts of dropped packets can occur on my side even on a good connection, I need to revise my thinking.
So what's important is to document the issue the best we can and spread the word until soemone who can do something does... I hope Tony and MacMan take notice since I guess they can either fix it ot better spread the word.
Or if I am wrong in thinking the problem is in the driver, I'd like to know...