Mjolnir - I've had a Fuji HS10 for almost a year, and have been active in following the Fuji forums about this camera.
While, so long as you stick to the Priorities Modes and Manual, it's a pretty good bridge camera for stills - and fast Continuous at up to 12fps, and is also good for a P&S in low-light / high-ISO situations - it is not at all a device you'd buy for doing anything other than very casual hobby video.
I cannot describe the HS10's user or manual Video Control functions, as it doesn't have any....
There are no Video Manual Focus or Brightness adjustments. There is no "Video" mode on the Modes Dial. Resolution - 1920 x 1080 / 1280 x 720 / 640 x 480 - is Menu-select only.
There is no "shutter button" Video Start-Stop. The Video is both Started and Stopped via the Red Video button on the back of the camera. This means that unless on a tripod - the camera has to be re-positioned to start and stop Video. When starting to Video - there is a delay of several seconds after pressing the button before the Video-ing begins.
While in theory the barrel-type twist-zoom suggests good and variable rates Zooming while Video-ing - in actual use, that's just a wild dream... While quite excellent for stills - very fast and accurate zoom and "frame-fill" adjustment - for video ANY smooth adjustment isn't possible.
The "start" of rotation of the zoom-control "jerks" - and any attempts at movement while Video-ing "jerk" at start and stop of rotation movement. Also - in any zoom-change - the Focus is "leisurely" to catch-up - and the focus-function is very audible in the Video-audio. Fuji should call the Video Zoom - "Jerk-O-Matic"....
The "best" Video with the HS10 is at any position of Zoom - then left there... Use the Shutter button to "pre-focus" in stills mode. Then press the Red Video button. Pre-focusing seems to reduce the "delay" before the Video-ing actually starts.
Don't "aim" from a light-to-darker area - as there's no Brightness compensation - in camera or manual - after Video-ing starts - the resulting clip will "dim-out" going one way - or "flare-out" while going from dimmer to brighter areas of aim.
Note that the Std - 1280 x 720 - Video is noticeably better quality than the HD - 1920 x 1080. While the supposed number of pixels per frame more than doubles between those - there's not a lot of difference in file-sizes per-minute...
If I'm just doing short clips - a minute or so - I use the HS10's 1280 by 720. If I want to do "videos" - I just use the H264/MOV 640 x 480 in my Canon SX10... That has the 2-speed power zoom the HS10 doesn't - and the Manual Focus and Manual Brightness the HS10 doesn't.
As for the HS10's High-Speed Video - yes, that works. The 120fps 640 x 480 that plays back at quarter-speed is quite usable. The HS Video has a 30-second limit, and there's no Audio with it...
I suspect that Music Videos work better with Audio.
A Canon SX30's very good, if only Std HD - Video functions - makes the HS10's Video "abilities" look as if they came from Noah's Ark - with apologies to the good Noah...!
I haven't used the FZ100 Panny - but if you're "only" choosing between that and the HS10 - if the FZ100 can "beat" the older Non-HD Canon SX10 - it's waaaay
ahead of Fuji's HS10 for Video....
I love my HS10 - now I know to avoid Auto, Program - and Video - Modes....!