Hello~!
Hm... I'm not sure why the emotes wouldn't be working. Just to confirm, you went through the whole authentication process and allowed the app to get information from your Twitch? (Also, it was a Twitch emote and not a BTTV emote, correct?) They should drop within a few seconds of being posted in chat. If they still aren't working, let me know and we can troubleshoot further.
And yup! All the chat commands require the '!' symbol before them. So based on your video, you'd type "!walisi" in chat and it would clear the screen.