FLVs are no longer supported by browsers as they require Flash to be reproduced. All browsers have removed support for Flash, so the updated AllVideos version merely puts a link to the .flv file so it can be downloaded by users.

FLV, Windows Media, Quicktime and other old/non-web-friendly media will have similar behaviour as they require add-ons in the browser.

Modern formats like .mp4 or .webm are natively supported by browsers and have a better size/quality ratio compared to the older formats.

Simple: {webm}path/to/file{/webm}