It is a connectivity issue, it is happening because the tv cannot access the youtube servers.
There were some recent (within the past week or so) updates to the youtube server environments, and many tvs and other smart devices lost compatibility because of it.
On most devices, it is a simple matter of installing a firmware update to restore that compatibility. In this case though, that is unlikely to happen. This is a 2013 model, which means it is past the age that vizio is supporting it, so they likely will not put forth the effort to develop and release an update. They generally support their tvs only for the first year or two at the most. You can wait for an update, and if one ever comes it will be automatically installed by the tv, but if one does not come, which is what I expect, then the app will no longer be usable on this tv. You'll find that over time other apps (like amazon) will stop working as well, which again is common with this brand as they stop updating.
The next best option in that situation, other than buying a new tv, would be to connect an external streaming device like a roku or fire tv, and get all the same functions and many more, with better performance, long term support, and lower cost.
My apologies for the news.
If you have any other questions, just let me know. Otherwise, please take a moment to rate my service as this is the only way I am credited for my time. Hopefully I have earned 5 Stars but if not please let me know what I can do to ensure you are satisfied. I also invite you to contact me directly with any future support needs at http://bit.ly/1QwLxGh and ask for Nathan.
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