In an effort to track my progress on this workflow, I am using Reply vs. Edit on the original post.
Updated edit includes:
moving from Run NSAppleScript to Run Script using /usr/bin/osascript which in turn runs the AppleScript in the Script window.
adding "Enter your Meeting ID" as SubText (see screenshot)
removed GTM version specificity by deleting:
tell process "GoToMeeting v7.1.8"
and replacing with:
tell application process "GoToMeeting"
The net result of this should be that any version of GoToMeeting will now work with this workflow.
I tested with current version 7.1.4 and older version 6.4.12 build 2331 and both versions work.
Also, this workflow has been tested on 10.10.3 and 10.10.4 beta.