RME has not only one recording interface, which one do you have ?
Never heard of an application named "video screen". What is the programs name and installation path?
I want to find out, whether this software can make use of an ASIO driver or whether you need to configure WDM devices in the RME driver settings dialog.
I currently assume that your video application is not capable of using an ASIO driver. So maybe you forgot to configure WDM devices for the analog outputs to which your speakers are connected to. These WDM devices are needed for Windows 10 and all Windows applications which do not support ASIO.
Assuming you connected your speakers to Analog 1/2 OUT then you need to:
1. enable a WDM device for this particular output in the RME driver settings dialog.
2. open Windows sound settings and make the WDM device for Analog 1/2 OUT to your systems default sound device.
Once you did this, then Windows and all applications, which do not support ASIO, should be able to output sound to your speakers via Analog Output 1+2.
If you playback music or a video, then you should see the signal arriving in TotalMix FX in the Middle row "Software Playback Channels" Analog 1/2.
Now check your routing in TotalMix FX that sound from Software Playback Channel 1/2 is being routed to the Hardware Outputs Analog 1/2 (bottom row of faders).
Follow this procedure:
Ensure in TotalMix FX, that you still have "submix mode" enabled. In the bottom row (Hardware Outputs) click to the fader "Analog 1/2". Now you see the submix for this Output Analog 1/2. Ensure that you see sound arriving at the Software Playback channel Analog 1/2 and raise the fader of this channel slowly so that you do not overload your speakers or damage your ears.
That is basically all which is required to enable Windows and non-ASIO aware applications to send sound to the RME WDM device Analog 1/2 OUT and to configure routing properly.
Once you are satisfied with settings store this as snapshot 1 (on right side of TotalMix FX) and name it i.e. "speakers" so that you can easily recall these settings.
Now you should safe all TotalMix FX settings (snapshots and workplace).
BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub13