Which video editor can I use to make clips to upload? [duplicate]

I like OpenShot, but you can find a full list here. Take a look to Linux section, eventually you can search in Software Manager for the given keyword.

I had a great experience with Kdenlive which is also in the default Ubuntu repository. It has a bit more functions than the OpenShot and seemed to me more robust.

I suggest you try out Shotcut (http://shotcut.org/bin/view/Shotcut). It a cross-platform video editor translated in many languages whose developpment is led by Dan Dennedy former developper for Kdenlive. It's really simple to use with a drag n drop concept, filters (text, video, audio) and you get great results very quickly. one thing that stands out is, that there's no need to "import" clips into a project just like you do with Kdenlive and Openshot. The lastest version came out a couple of days ago (attention: new versions are 64bit only).