way to edit an encoded video

Is there a way to modify the encrypted video to blur certain portion so that

when it is decrypted by the qc team it is either blurred out or blanked out.

I can do this on the decrypted video but would like to know if it can be

done on encrypted file.

OR

Can I edit a portion of decrypted video and encrypt it back? If so, could

you send me the instructions.

The reason I want these to be saved back as Raw files is - whenever someone

tries to transcode these it will already be edited(the portion that I need

blurred or removed).

My system works this way.

1. QC agent logs in to the CRM.

2. They send a request for a video file.

3. Video file is then downloaded from the server, transcoded and

played in a media player.

It is after step 3 that one realizes the need to edit the file. So it has to

convert back to raw file, so the next time someone requests the same file it

already has the required modifications. Can this be achieved?