The issue I have with having multiple files recorded is that short sections of the game video and audio, as well as any commentary I might be making at the time, are missed during those transitions when Jazz switches modes, due to Fraps having to stop recording the old file and start recording to a new file every time the game's resolution changes.
On a not-capture related note, this also causes playing in full-screen mode (with or without aspect correction enabled) to freeze briefly every time the game's output resolution changes, due to having to re-render the output to fit the screen.
I feel that having DOSBox respect the intended display mode and draw the game's output into an output at that size would solve both of those problems (albeit only with aspect correction enabled, which would be necessary for an accurate representation of what the game looks like on real hardware in real DOS anyway).
At any rate, I'm totally aware this feature request may never actually be implemented, due to it not at all impacting the ability of the game to be played in what I guess is more typical use cases (windowed mode, likely with 2x or 3x scaling, with or without aspect correction enabled...), and only somewhat impacting the game in full-screen mode at high resolutions, and multiple recordings can be stitched together even if the end result is slightly less than accurate to the actual gameplay (and at less important moments rather than during actual gameplay).
I only brought it up because I thought it was a good idea, and in case anyone else might think it's a good idea.
EDIT: Based on some further tinkering it has come to light that my request may, unfortunately, be extremely difficult, if not impossible, to emulate in software. I hereby rescind my request.