While it is hard to determine how common it was, and how often a regular peasant or his family in Medieval Sweden would see such acts, it was common enough that several of the Medieval county laws included special (and deplorable) laws regarding the legal status of travelling entertainers. The Swedish Medieval county laws had long oral traditions dating back probably hundreds of years -an unnamed priest in Vidhem added a series of elected lawmen going back around 250 years in 1240, the oldest being called Lumber and would have been interpreting the law for the people of Västergötland around 990-1010. He is mentioned as being buried in a mound since he was a heathen (ie of the old Norse pagan faith).

Östgötalagen (the Medieval county law of Östergötland Öland and parts of northern Småland, the oldest written copy that survives is from around 1290):

Nu uarþær lekare dræpin, þa böte arua hans þriggia iamlanga gambla kuighu okköpa hanum nyia hanzska ok nyia skoa ok smyria baþe; þa skal taka kuighuna ok leþa up a högh ok hålan i hand arua leka-rans sætia. Þa skal bondin til hugga mæþ gisl þry hug; far han haldit, haui at botum sinum, slippær hanum kuighan, þa slippe hanum aldær faghnaþær.

My translation:

When a travelling entertainer is killed, to his heir is fined a three year heifer and he is bought new gloves and shoes, both of which are greased. The heifer is led to the top of a mound and the tail put in the hand of the heir. The peasant then whacks the heifer three times with the whip. If theheir can hold on to it, he has his fine. If he loses it, he loses all compensation.

Some historians argue that "lekare" refers to all kind of rootless travellers without a position or steady source of income, however, the Västgöta law (oldest surviving written copy we have is from somewhere around 1280) specifies "lekare" as "going with fiddle, violin or drum", which would identify them as musicians. The Västgöta law does not state that these people are completely without legal rights as the Östgöta does - killing them is not extempted from punishment, but beating is. And wounding them creates a very similar scenario to the one in the Östgöta law - with a heifer with a shaved tail and greased shoes.

So, the bottom line here is that while we can't know for sure how common travelling actors and musicians were, the free-holding peasants that wrote the laws and elected law-knowers to interpret them obviously knew of their existence and clearly despised them, not offering them the same protection of the law as people living on the land. To answer your question, the average Medieval villager were probably familiar with some kind of acts by travelling entertainers, as they saw fit to make special laws regarding them.