ffmpeg.dll is a application which is probably NOT a virus. So, if ffmpeg.dll is on your PC, it is probably ok, and will NOT be a cause for concern. Even if your system is virus-free, we still advise you to use a good antivirus with a good track record, in order to yourself yourself against viruses and malware.
Usually, this program is stored in C:\Program Files (x86)\DsNET Corp\aTube Catcher 2.0\ffmpeg.dll.
The MD5 fingerprint for this program is b21d7acf07e5e6ffdc66fa2af23f8f84.
This application does NOT operate as a Windows service. This is usually a good sign.
This executable runs in 32-bit mode. It does not benefit of the full set of features of current PC CPUs. This is quite normal because the makers did not bother to upgrade it to use the x64 instruction set.
This task does NOT have visible windows. This is most likely a bad sign.
The digital signature is missing from this program. The maker did not sign it. This is probably bad.
It has an uninstall string in registry, which is a good sign. si are uninstall.