Preferable platform for video-editing and viewing - Executable program / Web-based?
I wouldn't use any of those: Browsers can't handle the weight of an application like that, python would take ages to render. If you want to make the frontends in python and/or HTML/JS feel free but you will need a compiled (Preferably C/C++) application to handle the heavy lifting in the background (For HTML, especially if you plan on making it actually have a working preview)
You'd have more luck with flash than with HTML for this...
I need to make a light-weight application for video editing and viewing.
I was thinking of either writing an executable program written in Python, or a light-weight web app using JavaScript and HTML5. Flash, as a third option, is pretty much out of the question, since it's too fat and has many security flaws.
EDIT: The video serving itself (read: the "heavy-weight stuff")  will be done by a dedicated fast library or service. Thus, the Python/Web-app questions is pretty much related only to the GUI and some very basic video manipulation, like jumping to a specific frame and such.
What is the preferable platform, considering speed and ease of use (for the user)? Should I just use Python, or maybe just build a small web-app for my task?
Thanks in advace,
Ory