Your Untitled.mp4 clip will work like an individual clip, and fade in and fade out should work just fine.
You aren't seeing it on the clip because you have the "Rubber Band" set to display ObjectTracking, as indicated along the top of the clip.
Click on the top of the clip and set the "Rubber Band" (the yellow horizontal line that runs through the clip) to display Opacity and you will see the fade in and fade out.
If you still don't see them, post another screen shot and I'll figure out what's up.
Thanks for your reply.
If I right-click on the yellow bank and select Show Keyframes and then Opacity, it allows me to fade.
Is that what you mean?
Yes. Is that what you're looking for?
Yes, that's great.
Many thanks again!
Glad I could help, Steve!