If you want to try using Reaper as a slave with Biab/RealBand.
1.Install LoopMidi or LoopBewww.tobias-erichsen.de/software/loopmidi.html www.nerds.de/en/loopbe1.html
(Sends MIDI directly to an output port. Now can also send MIDI clock & song position pointer.)
Put that in a vsti plugin slot set it to MTC and LoopMidi or LoopBe.
3.Reaper/Preferences set Midi Device Input to LoopMidi or LoopBe click enable input/control
4.Reaper right click Play button set to MTC LoopMidi or LoopBe and Enable Synchronization.
5.Biab Drag tracks to Drop/Wav, Drag into Reaper
6.Biab press PlayBiab & Reaper Settings
I used the ASIO mixer VoiceMeeter Banana
set Reaper to Voicemeeter ASIO and BB to Voicemeeter AUX ASIO then the output to the audio device.
RealBand is good as it has the MultiRiff function.
So you can have your Biab and/or recorded tracks in Reaper then use RealBand to generate up a suitable riff/solo section to fit them,
then drag straight out into Reaper, disable the synced Play button then mix it.
You can open your SGU chords in RealBand, just uncheck "Auto generate song..." in Prefs - Song Generation first.
You should be able to do the same with Sonar or other DAW's the support midi sync slave along with the video track.
Reaper has the Exported Video in a track,
Reaper - View -Video
BB - Edit - SongForm - Unfold
Save As Youtube Video, check Scroll ahead.FormatFactory
don't install any extra software that comes with it just cancel out.
Convert BB Video.avi to Video mp4 see settings in bottom pic attached. In the Video Stream Settings enter the same, this will compress the video from around 50meg avi to 5meg mp4.
Rick click to Save >RealBand & Reaper Settings