1. UpdateMedia will take some time to find all your media and add it to the database if there's a lot. Leave it over night.
2. Check in the file sync menu of the web admin - browse into your media, on the right a big green tick means scanned and in the database, a big drive icon means it can see it but it hasn't been scanned in yet. Confirm that at least some are being added bit by bit.
3. In the devices tree confirm that the share has the "online" tick box ticked
4. Most importantly - in the UI if you are sorted by anything other than Filename, any media that is not tagged will not show up. Almost certainly your video will not already be tagged and therefore invisible. Choose Filename sort mode to begin with to confirm you are getting something.