@ agruts
Firstly, Ed's tutorials above should help to give you some insight into the process.
Personally, I would consider the 'stinger' as a simple overlay with a customizable "cut" point behind it as opposed to a "custom transition" which kind of implies a 'Special Effects' type of transition, although it is essentially a 'personalized' or 'branded' transition, hence the term 'custom'.
The 'stinger' will only 'cut' from 'Preview' to 'Program Out' so it is important that your 'overlay' video or graphic fills the screen at your chosen cut point, otherwise the 'cut' will be seen.
Ed's video talks about an image sequence, the 'stinger' can be that, a graphic or a video with alpha channel or a color that can be keyed out (all will work).
As pointed out in Ed's video, any of the 'overlay' channels can be set-up to function as a 'stinger transition' but I would avoid that and stick to the actual 'stinger' channels in the "Overlay" settings (button at lower right of screen).
Once there, select either 'Stinger 1' or 'Stinger 2' from the first drop-down menu and continue to "set-up" that overlay channel.
(Channels 1,2,3 & 4 do not allow for "Stinger Input" but will 'cut' to 'Preview' if you select a "Stinger Cut Point", again, avoid this unless you absolutely know what you are doing)
The important things here are to select the "Stinger Input" you want (video or image sequence) and "Stinger Cut Point" in milliseconds or frames.
The "Duration" is the amount of time the video or image will display (in my case, my replay video is ten seconds with "INSTANT REPLAY" text overlayed that I usually set for 7000 milliseconds. You can download my sample stingers
here).
The "Effect" and "Effect Duration" is the actual transition to the 'stinger' and not the 'transition' between inputs.
The next step is to 'set-up' a means of "accessing" the 'effect' or transition...
This can be accomplished with any of the 'Dropdown' menus for transitions in the center of the screen.
Choose the appropriate 'Stinger' you have set-up.
(Remember, the 'effect' only transitions from "Preview" to "Program" so make sure the next input you want is on the "Preview" screen).
Alternatively, (and I might add better, in my view) it is advantageous to set-up 'Shortcut Keys' to trigger the effect.
(In my case, I use advanced options to send the input to preview and play the stinger transition, or with the new "Replay" feature you have the option to set-up the stinger as part of the transition, in any event, that is somewhat of another "tutorial" on how to do that).
I hope that helps some and gets you well on your way to using the "Stinger Transition" feature of vMix.
Here is a link to how I use the 'Stinger' for instant replay:
And a link to other tutorials on-line:
Ice