I managed to get this working by installing cordova on my machine, then running the
sencha cordova init
command on my sencha project folder. After that I simply made sure allowsInlineMediaPlayback was set in my cordova config and that my video tag/object in Architect had the webkit-playsinline attribute set to "1".
If you're interested I am still able to continue my normal development and build workflow in Architect (Architect is now compatible with Cordova, though make sure you add
{ "path": "cordova.js", "remote": true }
to your app.json manually. Note you only need that entry in the js section of your app.json and DO NOT NEED THE ACTUAL CORDOVA.JS FILE TO BE IN YOUR PROJECT FOLDER, Architect will handle this when you run your build command).