I think you’re referring to the interface tools plugin. This is clearly allowed since it was made when paid plugins were allowed on the resources page (they seem to have changed the rules without notice).
There’s a bug with the topic’s image. Do I really need to DM?
I somewhat like the UI, but the text where you switch from Position to CellSize in the video is not enough. The anchor editor’s grid should also be customizable to an extent.
A gradient creator, preferably with some gradient presets would be nice to include (if not already).
Here's a gradient that I use
goodGradient.rbxm (620 Bytes)