Sorry for necro, but what editor can you recommend to someone, who's never tried video editing? I don't need to do something very fancy, just replace video sequence and add audio overlay in some places.
Davinci Resolve, it's free AND stable. It's also got a new(ish) quick/youtube mode for cranking out shit fast. It can run on a cheap i5 laptop using Intel IGP if kept under maybe ~4-5 minutes.
Some tips to get you going.
There are two gotchas: autosave isn't turned on by default and the same is true for pre-multiplied alpha, confusing if using images or video with an alpha channel. A third one, if you import a series of images with the same name and sequential numbering, like "Overlay1, Overlay2, Overlay3", it will be imported as a clip and not as individual images. That's just how it is and the toggle to stop that seems to have been removed for reasons unknown.
Keyboard commands: Backspace and Delete is not the same, delete not only removes the clip and audio but it also removes the empty space it would leave behind and
that applies to other video and even audio tracks, backspace just removes the clip.
Quality of life stuff:
Ctrl-c then alt-v pastes only the (user defined) attributes to another clip(like audio levels, cropping/scaling and lots of other shit you don't want to do a million times).
Instead of dragging a long video into the timeline and cutting it there, double-click on it in the media pool to open it in the viewer and mark in/out(i and o on the keyboard) the sections you want and drag it onto the timeline or back into the media pool to save them as sub-clips. Create separate bins(folders) for those to keep things organized. Use the arrow keys to move frame by frame(hold them to play at normal speed).
If you end up with a composite section containing tons of video/audio/graphics/effects stacked on each other and it looks messy, make that into a compound clip. A compound clip appears as a single video/audio track and makes things look tidy, it also gets added to the media pool* and can be decomposed into its original form at any time if something needs tweaking. Give those a different color and come up with a naming scheme.
*meaning you can put them together in a separate, empty, timeline(right-click in media pool, "create new timeline") to ease up on resource use. Then add the finished compound clip to the main timeline from the media pool.
It's not that hard to learn the basics, you just need to learn where things are. The learning curve to go from nothing to being able to make a shitty CS GO highlight video set to music is maybe 45 minutes for someone computer literate.