OSX Mavericks seems to be having problems with streaming uploads in general, but in particular, I can not stream videos with FMLE at all. I tried it with my accounts at Ustream and Justin and they have the exact same results, with the stream pausing and going black after just a couple minutes. It doesn't seem to matter what my output settings are; this will happen even if it's set for extremely low bandwidth.
This did not happen when I was using Mountain Lion. I am almost certain the new OS is causing the issues, but I am not sure how or why, and am having trouble finding others with this problem.
Other programs I am using in conjunction with FMLE are CamTwist and Soundflower