All that this custom action does (there's only one single custom action in that keymap file) is split the item(s) and place the crossfade so that it
ends at the edit cursor position (instead of the edit cursor marking the
middle of the crossfade area). As the maker of that video (sorry, forgot the name) places his splits rather loose - with some caution room towards the transient, I never understood why he made such a big point of that custom action
. He could have done pretty much the same thing using the regular Reaper action.
Still, it is a useful function when you need your fades placed more exact. Of course I am not the only one wanting this behavior, so the functionality of my custom action has in the meantime been nicely realized by Adam (Wathan, I think is the name?) and is included in the SWS extensions as
"SWS/AW: Split selected items at edit cursor w/crossfade on left".
Preceeded by "View: Move edit cursor to mouse cursor" in a custom action you have pretty much what I did back then - without all the cursor hopping and time selection juggling I needed to do in the background
Long story short: Nope, you don't need that file anymore
.