Video editing

I would like to produce a video similar to shorturl.at/flmEV

I will provide 6 short video clips and I need them merging together into a single video.

Each clip will be approximately 2-4 seconds long. The total video length will be no more than 24 seconds.

I will require any/all sound to be removed from the video to ensure a small file size for web use.

I will require some guidance ensuring the edited video is optimised for use on the web, in terms of filesize, resolution and compression.

I will require an overlay on the video with an opacity.