If you have a YouTube account, you can turn your score on MuseScore into a video on your YouTube channel. Check out what other MuseScore users are posting on YouTube.
You can find the 'Send to YouTube' feature behind the three-dotted icon ⋮ next to the score title. If you haven't connected your YouTube account to MuseScore yet, you are requested to do this first.
By default, the YouTube video created from the score will play with the same sound it does in MuseScore with all default Synthesizer settings. However, if you have separately created an audio track using different sounds, as long as the tempo matches up, the 'Upload audio track' button at the bottom of the page allows you to upload an MP3 that will serve as the audio for the YouTube video. Combining this feature with the ability to set a YouTube video as a score's audio source allows you to make your score on MuseScore.com play from a custom audio track instead of the default playback.
'Send to YouTube' can be used once per day with a free account, and is unlimited with a PRO account.