: Some media players display this text as an overlay when a playlist is empty or when the connection to a video server is lost. Is it a Virus?

The string appears to be a concatenated error message or metadata remnant:

This is almost certainly a slight corruption or highly specific abbreviation for "No Onsets" or "Network Sets." In environmental monitoring, an "onset" refers to the beginning of a specific tracked event, such as the start of a storm, a solar flare, or a seismic shift. 2. "Ec" (Error Control or Environmental Conditions)

ffmpeg -i input.mp4 -c:v libx264 -c:a aac fixed.mp4

If you find a file with this name and want to investigate or use it: