I did not find any activities on viral exchange today for twitter/face book,does it mean the bounty is closed or has it been stopped for a certain period?
I think all tokens have been claimed, however, they make an announcement here when they add new tasks, just check this thread daily.
You can check for youtube, they have youtube tasks as well.
I wonder why in twitter task I didn't see any coin yet which I can earn, that's only TVE points in twitter task, As you mentioned Zrcoin and Humaniq token has been listed in TheViralExchange. I just think, am i late to earn, or there any limit for a day, as I see in their thread they always announce a information which a new task has been post in TheViralExchange.
When a campaign owner add a new task, he specifies the number of actions he wants, for example: he wants 100 retweets or 200 likes. After this number of actions is reached, the task is no longer visible. This is how things are going on TVE. If you don't see any task, then you are late.
If you have seen some tweets and retweets, post on facebook. This answer your question