The replay programs do not record video. They only record instructions for MSFS to fly the plane. It’s kind of like MIDI vs. Recording for music. It’s only a list of instructions. So the computer generated stuff you see on screen is regenerated each time you “play” the “fly like this” (fly) instructions. In fact you can change aircraft and still use the same fly code/file. All of the “AI” stuff like vehicles, weather, ground crew, pilot movement, etc. is randomly regenerated with each replay. That’s why you don’t see the same weather. Having said that, not all of the replay solutions record all of the things that can be recorded. For example, MSFS Replay does not record what it takes to generate aerobatic smoke (smoke on/off), tire smoke/dust, etc. Sky Dolly (SD) saves and plays back everything that MSFS allows. Also, it’s the only one that automatically saves the replay files in a data base that greatly simplifies choosing what to replay. Also, you can position in the timeline and record from there (but I digress). The fact that MSFS can replay drone-camera-only is because they have an inside track on the code, that isn’t provided in the SimConnect data that other replay solutions use. To get the true live recording of what you see on screen you have to do a screen record. FCR has this built-in. SD does not as there are screen recorders (such as GeForce Experience) that operate a the “root” video level and thus are more efficient (less hardware overhead) resulting in smoother and more accurate recordings.
P.S. When doing screen recordings for videos, be sure to set the Time-Of-Day to be the same on each clip you replay for screen recording. Otherwise the shadows/sunlight in your clips will not be consistent. Unfortunately MSFS does not save the date and time when you save a weather configuration (oh bother).