TOR makes your IP address anonymous - so perhaps a block for devices accessing Rumble via Comcast has been put in place somewhere in the system. If the internet cannot see your IP address and thus that you are accessing via Comcast the stream is allowed to proceed... it implies that Comcast access is specifically being blocked.
Just to add, that in TN (Murfreesboro) I can’t access the sites mentioned plus Redvoicemedia and I assume other sites that use rumble for the video portion. I can get some items to come up, but not videos. My home connection is xfinity/comcast. Using my Verizon hotspot from my phone they all work fine. Also, if I use a TOR connection in Brave the comcast/xfinity connections works fine.