I have noticed when i try to right- click on certain videos i try to download on the net, it appear a small icon on the upper left corner of the video saying; 'kvs player v6 '. I have tried several conversion- methods to transfer the video into mp4 and download it, but with no success.

You can find full information about the update on KVS forum: KVS 4.0.4 update
What's new in 4.0.4:
Kvs Player Downloader For Android Chrome
Bugs that have been fixed:
Kvs Player Downloader For Android Windows 10
- Player not working on new Android 9 phones. This issue is critical and affects all KVS versions starting from 3.9.0.
- Push notifications JS file updated as required by advertiser.
- Grabbers plugin will show better progress indicator when grabbing a big set of videos or albums from a single list URL.
- Background tasks that deleted video format or timeline screenshots iterated through all videos and could result in long operation time for slow storage server connection.
- Removed 200 characters limit when configuring storage servers load balancing by countries.