It would be nice to be able to play the camera without needing to press "t" then clicking the button every time.
The real reason why I want this to be added, though, is because I would rather use my own screen recorder instead of the renderer and pressing F1 to hide the controls after clicking the play button keeps my mouse visible. Being able to start the camera path without leaving the movement controls would solve this issue.
My screen recorder also has a decent editor that I use to edit most of my YT videos, so having to export a video from Replay Mod to importing that into my screen recorder to edit with the rest of my footage is 2 more steps and a bit of time that I would save if I recorded it with my screen recorder instead.
I'm also more familiar with the settings and codecs used by my screen recorder and already spent a bit of time optimizing them.
The biggest reason is that a 5 second clip takes Replay Mod more than 15 minutes to render on my computer, but ScreenFlow can do it in 30 seconds. My computer also locks up a bit more when rendering using Replay Mod.