I can now confirm this does work. I have tested this with multiple video files using the same .srt file.
I tested it in QuickTime player, and I had to enable Closed Captioning every time I opened a url, but it did work.
You can add these properties to the TimedText/Properties section in [install-dir]/conf/Application.xml to help troubleshoot.
I intentionally tried to access a .srt file that didn't exist and received this error in the logs:
When it is working correctly I get this in the logs:
INFO server comment - VODTimedTextProviderBase.indexTimedText caption file:/Library/WowzaMediaServer/content/sample.srt does not exist.
INFO server comment - VODTimedTextDelegateBase.narrowProviders[vod/_definst_/VideoEdit.mp4]: No providers.
INFO server comment - VODTimedTextProviderBase.indexTimedText using file:/Library/WowzaMediaServer/content/sample.srt for captions (VOD:/Library/WowzaMediaServer/content/VideoEdit.mp4)
INFO server comment - VODTimedTextDelegateBase.narrowProviders[vod/_definst_/VideoEdit.mp4]: provider: vodcaptionprovidersrt