I use GNOME Subtitles to edit my subtitles. Is there any tool which works with video playback to code subtitles? I saw some screenshots where a subtitle tool has a video running inside it, allowing users to add subtitles easily.
Try gaupol. You should find it in the software centre, or will be able to install by running the following command:
sudo apt-get install gaupol
I don't know how I missed. Gnome-subtitles also have the option to author subtitles based on a playing video.
All you have to do is open a video through Gnome-subtitles
In the Video menu, choose open
Here is the process in action