Services like eBay are part platform, part people. eBay’s people do a lot behind the scenes to ensure it runs smoothly and ethically… AND they take a significant chunk of the proceeds. You could put up some free software that does auctions but you wouldn’t have all those high paid security and trust workers working for you.

That’s was all to say that just any video editing software will get you there. Pick one and try cutting where it makes sense. Look up how to crossfade in the software you choose.

This is a core capability for anyone who calls themselves a video editor, and all video editing software can support this easily.