Unluckily enough for you, Ripple Edit doesn't work with any item edge drag action.
It's simply not implemented in Mouse Modifiers > media item edge > left drag.
(although would be amazing if it would be implemented, i can see the benefit of how it works in Vegas).
But.. i am pretty sure you can create a Custom Action for what you are doing at 0.05 in the video and a Custom Action for what you are doing at 0.15.
I just have to figure out these 2 Custom Actions in my head
The benefit of these Custom Actions would be that you don't have to mouse drag at all, (mouse dragging is cumbersome, too timeconsuming!!), you just left mouseclick at the position on an item where you normally dragged the item edge to and then execute Custom Action with a keyshortcut: fast workflow !
EDIT:
So here is the first Custom Action, for what you do at 0.5 in your vid.
https://www.dropbox.com/s/04vv537q1u...perKeyMap?dl=0
- Import this Action into your Reaper Action List and assign a shortcut to it.
Howto:
Leftmouse click on the position of an Item where you would normally drag the right edge of the item to.
Execute the Custom Action
Presto !
EDIT2:
Here is the second Custom Action i made, based on what you do at .15 in your vid:
https://www.dropbox.com/s/oww0a1k9ub...perKeyMap?dl=0
- Import this Action into your Reaper Action List and assign a shortcut to it.
Howto:
Leftmouse click on the position of an Item where you would normally drag the right edge of the item to.
Execute the Custom Action
Presto !