Other contributors have said "How many people can be entertained at a time?" is the same question as "What entertainment was available to people during medieval times?" If you believe that these are not asking the same thing and should be answered differently, click here
What entertainment was available to people during medieval times?
They really did the same things that any of us would do if we didn't have modern technology: talk eat party sing dance go for walks or runs garden compose or listen to music paint pictures, draw,...
Not much. If they were lucky the local church would have a passion play or the local noble would have jugglers come in or others to perform. Most of their time was spent trying to stay alive and work.