Younow has changed their website such that you cannot see any user's profile unless you log in. So, it is now impossible to probe for the existence of a username.

data.json

@@ -1118,15 +1118,6 @@
     "username_claimed": "blue",
     "username_unclaimed": "noonewouldeverusethis7"
   },
-  "Younow": {
-    "errorMsg": "pageTitle || 'YouNow - Broadcast Live",
-    "errorType": "message",
-    "rank": 13248,
-    "url": "https://www.younow.com/{}",
-    "urlMain": "https://www.younow.com/",
-    "username_claimed": "blue",
-    "username_unclaimed": "noonewouldeverusethis7"
-  },
   "Zhihu": {
     "errorType": "response_url",
     "errorUrl": "https://www.zhihu.com/people/{}",