You just need any fairly small, lightweight video head with a quick release plate on the top of it. Most heads have a 3/8" hole in their base so you may need a 3/8" to 1/4" bushing insert to attach it to the arca style plate on the MeFoto Roadtrip Air.
The biggest problem you're going to run into is that the MeFoto Roadtrip Air is very lightweight. That's good for portability and travel. That's not so good for stability and camera control.
If you're only shooting stills the normal solution is to use a remote (wired or wireless) or timer mode to separate the force of operating the camera and the motion that induces from the time when the shutter is open. But if you are wanting the video head with a "handlebar" so you can pan while shooting video you may find that the tripod itself will not be stable enough to do what you want. This becomes even more of an issue when the center column is extended for additional height. Adding the weight of another head to the top of the tripod will only compound the stability issue.
The other thing to consider is that on the whole, arca style plates are generally considered superior and more rigid than QR plates such as the Manfrotto RC2 system. They also allow for front-to-rear adjustment to better balance the camera/lens on top of the tripod. This is particularly an advantage with a lighter weight tripod.
If you really want a video type head you might also consider the Benro Aero 2 Aluminum Video Travel Angel Tripod. Benro/MeFoto are the same company. The tripod is designed more as a video platform from the ground up. It is a bit heavier than the Roadtrip Air but the weight of the detachable video head is already included in the weight of the Aero 2.
