. . . . do i need to install QuickTime for some of my videos . . . .
If the program is saying you need to install Quicktime, then the video files are encoded either in PNG or JPEG formats for which Quicktime is necessary, download is here
However only install the Essentials components, these are normally selected by default.
Do note if the video formats are ProRes encoded then you may have issues with the no image and/or no audio.
Also note that this is an open forum and we have junior members, bad language is not permitted, @PATIENT-X has cited the Community rules - link is at the bottom of this page.