The rules for using copyrighted content are the same on FOSS platforms as for the big players, legally speaking. The difference is the FOSS platforms simply don’t have the same enforcement mechanisms in place, so they won’t give you warnings directly and automatically. If a rights-holder comes across something that uses their content, however, they can still come after you under the law using things like the DMCA.
The rules for using copyrighted content are the same on FOSS platforms as for the big players, legally speaking. The difference is the FOSS platforms simply don’t have the same enforcement mechanisms in place, so they won’t give you warnings directly and automatically. If a rights-holder comes across something that uses their content, however, they can still come after you under the law using things like the DMCA.