1) I do not know where VLC came from, was installed when I got the new computer.
2) Avid is one of the options under OPEN WITH.
3) I believe it is a problem with Avid, not the other media player, as any video file imported into Avid's library is shown with a grey screen with circled arrow, and when played is blank but with full audio. An included video that came with the product shows the first scene (in library), and plays well.
4) My computer is a Gigabyte brand Q2532 N Notebook, CPU Intel Core i5-2401m ; Memory 2*2GB, DDR3 ; Graphics NVIDIA GT 540m/1gb ; OS Windows 7 Professional ; I have an LG printer Officejet Pro 8500 and a Gigabyte mouse connected via USB, plus spare USB ports ; I use Synctoy to back up data to a removable Welland Hard drive.
Hope this is enough info .