It's not a beta build specific option & hasn't been moved from being a sub-node of the Playback node. Maybe you've already disabled the video support. If you go to Preferences -> Advanced -> top of the first tab -> if that has the 're-enable' button show as clickable then it means you'd already attempted to disable it.
It is possible to manually force the video plug-ins to get loaded after having used that option which might be the case since you mention you're using in_dshow for everything. So if that is the case, you'd need to click re-enable, then go back to the video prefs page (after a WACUP restart) & then click on the disable button to get it to a no video state again. Otherwise you may just need to adjust what in_dshow is set to use.
The only other thing is maybe you'd removed the Video prefs page & you'd need to click on the action part of the close prefs button to get to the menu that allows you to view the hidden prefs pages & check that for video being listed.
-dro