1) Perian is a playback framework for a wide range of audio / video codecs, which makes its ability available to all QuickTime using applications (among them QuickTime Player). One additional feature of Perian is, that it supports loading external text based subtitles files to a video such as SRT, SUB, etc, by rendering it as an an additional video layer to the video file it belongs (they share the same filename (or at least the same beginning characters) i.e. "Video.mp4" and "Video.srt" or "Video EN.srt"). In order to not have the option greyed out, but facilitate this feature, ensure this setting:
System Preferences > Perian > Load External Subtitles: YES.
2) VLC uses its own libraries for decoding A/V codecs, and does not use Perian, as far as I know. If it is "jumpy" then the solutions lies within VLC. You can try to set a time offset for subtitles in the menu, or maybe try another subtitle file, your's could be corrupt.
3) Another media playback application which I can warmly recommend is MPlayer OSX Extended
To have the finest experience with subtitles, I recommend to go to the applications Preferences > Advanced > And add the following two options.
- -sub-fuzziness 1
- -slang de,fr,en
The first option ensures that i.e. "Video.mp4" is not only associated with "Video.srt" but also with "Video - English + scene annotations.srt" ("fuzzy").
The second option allows you to set a standard language priority in case you have various language subtitle files for a video. Change the language codes and order according to your taste.