"The app doesn't work and crashes all the time," commented one person on Youtube's Twitter account.
"Youtube shuts down on and off when watching, it's annoying," writes another.
According to the reports on Downdetector, the app started crashing shortly after half past seven, on Thursday night Swedish time.
Thousands of users in, among other places, Sweden, Norway and the USA subsequently reported technical problems with the service.
What has caused the disturbances is still unclear.
The article is updated.