They were not so much forums, more like the name implied Bulletin Board Systems, you just left messages in a very crude forum.. Topic varied by the BBS you dialed into, and if you were lucky the SYSOP (system operator) was at the keyboard and you could live chat...
This is an example of a pretty elaborate one, most BBS in the day were even more basic... Pay attention to the speed the text flows and realize this guy is using a 2400 baud modem, my first modem was 300 baud or 1/8 the speed depicted in the video and I was excited to have that speed because 150 baud was still the standard at the time....
Wow! That's pretty neat!

LOL, computers back then didn't even play videos or display pictures by any practical means, you only had green, amber or white depending on your monitorThen everyone got excited when PCs like the Apple // and Commodore rolled out with a whopping 16 colors!!!