HBO Go stopped working for me on Linux recently (actually it might not have been super recent, I don't use it that often). Apparently a DRM problem with Flash 11.2.x on Gentoo (and other Linux versions I'm assuming), I was able to get it working again by emerging "media-libs/hal-flash" (version 0.2.0_rc1 I assume). I have no idea why HAL is deprecated.
The move away from Flash is going to eventually be OK, since it came with its own issues, particularly on 64 bit Linux. In the short term it has caused me a lot of problems.