Are you currently experiencing any server issues?
I ask because I just did a clean install of MC33 on a new pc and saw a delay in the Directx download then when I tried to play a video, I got the expected "Adding requirements" message when the LAV filters get installed on first playback. After a timeout I got the unable to play back error so I checked my network/firewall settings but didn't see anything obvious. I forgot to mention that I've already added the JRiver folder exceptions in Defender with no other AV
Thanks