So far, it seems to be doing good, but I too am having a few issues here and there with trying to do some uploads. At first, I thought it was an issue with the first vid I uploaded being a .wmv, then I was able to get a converted version of it to .mp4 which worked just fine.
Recently, I tried to upload a new vid yesterday and especially today/tonight, also in .mp4 format, but I got the same result from the .wmv vid saying that, after a 100% upload, I also got the "Invalid Extension" screen on both Chrome and Firefox.
The file size is only 24.5 MB, so hopefully, this new try for tonight will work, otherwise, a heads up on this.