Alright so I've been making this program that will log the title of a window to a file for streaming reasons, and although it's a bit rough right now, it could definitely work for your cause.

https://bitbucket.org/GeordieP/windowtitlelogger

Hooked up to Spotify, or a browser playing YouTube (and certain other players), it does work well enough. The problem is that right now, there's no feature to exclude certain strings, so the "Spotify" text, and x song "YouTube - Google Chrome" or whatever text will be there and there's no way to hide it (YET!).

For example this is what Spotify looks like on stream:
http://puu.sh/fjBmj/ed65083635.jpg
(oh god i just realized it logs spotify's - character as a question mark that's a problem uh i'll fix that )
And YouTube:
http://puu.sh/fjBxN/abb6ad7500.jpg

I use it on my own stream for music, so it's definitely workable. All you have to do is add the log file as a text thing in OBS and it's all lovely. Just don't forget to start monitoring the application, and switch the monitored process when you want to switch between YouTube and Spotify for example.

If you're interested I can upload my latest build, but keep in mind it is pretty basic right now.