Strange Issue with Live Flash Webcasts

I am having some issues on my computer related to streaming live flash-based webcasts. I can play pre-recorded webcasts from the same site on my machine, but when trying to view the webcast live, I get nothing but a black box. Other users here in my office are having the same issue, but it is not company-wide (i.e. Some users can view the live streams just fine).

I am running...

Windows 7 Ultimate x64 w/SP1

IE 9.0.8112.16421 (32bit)

Flash Player 10.3.181.34

I've tried changing the hardware acceleration and cache size via Flash Player settings, but nothing works. I've tried toggling the ActiveX Filtering settings in IE, but it also did nothing. For whatever reason, I cannot watch the live streaming webcasts (http://www.puco.ohio.gov/apps/Webcast/index.cfm), but the pre-recorded videos from the same site work fine. All other Flash video seems to be working aas well.

I would write it off as a problem on the video provider's end, but other users here in the office can watch the live stream just fine, and with seemingly identical (hardware and software) machine configurations.

Any advice?