AVI files are pretty passe by now, but I'm certain there are people out there (like me) who have gotten used to Virtualdub.
Sadly, Virtualdub will load most anything (with the appropriate plugin) but cannot save much of anything. So, unless you really like everything in AVI format, you'll need a new editor.
The question is: which one?
If you like Virtualdub for it's good keyboard support, easy clipping against keyframes, processing speed, ability to clip without transcoding, or anything else, you are probably going to want an editor that works like that for .mp4 files.
Fortunately, I only had to look around for a bit.
- I looked for Windows Live Movie Maker, but it only comes bundled with a bunch of other stuff, and I did not like that. I didn't even bother trying to install it.
- I tried Filmora Video Editor. Looks like a good editor for "real" video editing, where you merge multiple video streams and so forth. But the interface and output options are nothing like Virtualdub, and it seems too complex for simple clipping. I tried to clip a file and gave up in short order.
My third try, avidemux, seems to do the job. It has an interface and behavior similar to Virtualdub, seems fast, opens everything (avi, mkv, mp4, etc) and can save without transcoding. It will clip on and off keyframes, warns you when you're cutting off a keyframe, and handles off-keyframe cuts fairly gracefully.
(I guess I should have tried avidemux before. I admit the name put me off a bit. But then again, what kind of name is "Virtualdub" anyway?)
I have not tried avidemux for items like volume correction, video conversion or other things. But so far it's looking like a nice & fast editor for simple tasks.
For reference, here's a handy cross-reference guide of the basic controls for avidemux that you'll probably want to know/use.
Virtualdub -> avidemux
Next frame: Right arrow -> Right arrow
Previous frame: Left arrow -> Left arrow
Next keyframe: Ctrl-Right arrow -> Up
Previous keyframe: Ctrl-Left arrow -> Down
Start: Home -> Home
End: End -> End
Mark beginning: [ -> Ctrl-Page up
Mark end: ] -> Ctrl-Page down
Save: F7 -> Ctrl-S
Not guaranteeing I got all of those correct for Virtualdub, but they should all be correct for avidemux. Happy clipping!