Possibility to change thumbnails of video assets in AEM 6.4.3 version

@chinmayish 

Adobe Dynamic Media Classic generates thumbnails for encoded videos, and pre-encoded videos. You can use video thumbnails like any image asset. Moreover, you can obtain URLs for the video thumbnails that Adobe Dynamic Media Classic generates and deploy these URLs outside Adobe Dynamic Media Classic. For example, you can deploy the thumbnails in search results, related video listings, and video play lists on a website.

Refer below links -

Using Custom Video Thumbnail with AEM Dynamic Media | Adobe Experience Manager

Deploy video to your websites and mobile sites | Adobe Experience Manager