FLV files are just video, like MP4 or MOV files. Lectora might convert them to MP4 but it should be able to play them without using the Macromedia/Adobe Flash Player. And yes, older versions of Lectora used a Flash Player-based audio/video player, while reasonably current ones use “pure” HTML with no plugin required.
Now, if you or a previous developer explicitly added a SWF file to a course, then Flash Player will always be needed to view it. SWF files are specifically Flash Player files. (There are little-used alternatives to Adobe Flash Player, but what I’ve written is nearly true.)