Has something with the twitter API changed? This link was returning results earlier today but for whatever reason it seems to have stopped?
https://search.twitter.com/search.json?q=vine&callback=?
Also, clicking on the links in the examples no longer work?
If you're coding in ASP.NET, I recommend the Twitterizer library. It's written and maintained by a fellow who helped me get my own Twitter .NET library off the ground when I was doing that sort of thing.
Yes. You've found out how the version 1 api has been deprecated / is in the process of being removed.
From now on, all your requests to the twitter API will be required to have authentication (OAuth), and for some this was a nightmare to figure out.
Fortunately, I wrote a lengthy post (with pictures) explaining how to set yourself up a twitter dev account / application, get a set of keys, and then I created a library to perform authenticated requests for you.
The only downside is that this library is written in php, and from looking at your profile you use ASP.net - so try googling for a library for your specific language if you don't want to use PHP.
In any case, no more unauthenticated requests for you ;) You need to dig in with OAuth now!