Having set up one Kodi installation via HDMI on my TV, I now want another for my projector, using composite video. The Pi OS (Raspbian) is delivering composite just fine, and so does the Kodi home page, menus etc. But when I actually try to watch a video stream, some streams (eg YouTube) work just fine, while others (eg BBC iPlayer) do not. The stream is playing, as I can hear the audio, but all I see is the Kodi screen from which I launched it.
Update: I have tried a few more addons, and the problem seems to be related to the specific addon. This is what I've tried so far:
BBC iPlayer by Mikey1234 version 0.2.0 Live: audio only Catchup: audio and video
iPlayer WWW by CaptainT,Cas,ihurst,primaeval version 1.3.1 Live: Audio only Catchup: audio only
ITVPlayer by Mikey1234 version 2.2.6 Live: audio only Catchup: audio and video
Nasa by Tristan Fischer version 2.0.3 Live: audio only Catchup: audio and video
So it seems to be specific to something the individual addon is (not) doing, but it is also specific to using composite video, as everything is fine on HDMI.
Update 2: I have also now added the Gert VGA666 adapter, and can use that successfully in all cases that did not work on composite. This solves my immediate problem (as my projector has composite and VGA, but not HDMI), but still leaves me wondering why composite does not universally work.