McAfee Plus? Do you mean Security Scan Plus? That is not an antivirus but a sales tool that downloads optionally with such products as Adobe and others. It should be uninstyalled in the normal manner via Control Panel.
Maybe you mean something else, sorry.
FLV isn't a virus but more of a PUP, or Possibly Unwanted Program.
Run AdwCleaner linked in the last link in my signature below.
If that doesn't work run Malwarebytes Free, also linked there. To keep it free of charge do NOT accept the Free Trial.