I think the answer to this will lie in how much the (former) employee is prepared to do.
From the firm's side, the employee was effectively paid to appear in the video - they were on the payroll when the vid was made.
From the FE's side, they may not have been given to understand that their image would be put online.
So the first base is to establish how and when the form obtained employee consents to use employees in promotional videos and put them online (same applies to still photos).
When I last dealt with these matters on a daily basis, the law stated that organisations could only do so with explicit consent of indviduals, and that the consent had to be re-obtained annually.
Practically nobody followed this ruling.
Getting legal support that understands this issue and is affordable by the FE may be impossible.