* Prevent default event handling when clicking on the video position slider
This prevents accidental text selection when clicking on the position slider.
* Fix bug when clicking on video position slider before starting the video
* Slightly more aggressive video preloading
- Preload video metadata if the video is loaded in detailed view, as it is
likely to get played, and metadata is useful for seeking in the video.
- Preload video data if it's fullscreen as it is extremely likely to get
played right after being put in fullscreen (although those are two steps).
- Preload video data if the user has clicked the position slider, as the video
will play as soon as the mouse button is released, and video metadata is
needed to properly seek into the video.