I found a helpful method to use "Safefrom.net" extension on Chrome.

After Meddlemonkey was removed from Chrome Web Store,Here is reinstalling method:

1.Install Chameleon in Chrome : https://chrome.google.com/webstore/detail/chameleon/dmpojjilddefgnhiicjcmhbkjgbbclob

2.Then install "Savefrom.net" extension for Opera https://addons.opera.com/addons/extensions/details/savefromnet-helper/?display=en

3.Then click on "Install on Chameleon"

4.Finished.Work like Savefrom.net Javascript that run on Meddlemonkey.

P.S.In Savefrom.net extenstion v.9.33.2 (for any browser),There is no download button when hovering over video thumbnail in Youtube channel that work like download button in video page