Whenever I open Video from Desktop It looks Hours and Hours to download from iCloud Drive: What Services Apple iCloud proving

iCloud Drive is meant for storing files / folders and not for uploading videos Upload and download files from iCloud Drive on iCloud.com - Apple Support

You need to set up photo library from Mac Set up and use iCloud Photos - Apple Support

Download your photos and videos from iCloud.com

1. On iCloud.com, click Photos.
2. Select the photos and videos you want to download. 
3. Click and hold the download button  in the top right-hand corner of the window. If you want to download your content as it was originally captured or imported, choose Unmodified Original. For JPEG or H.264 format – including edits and even if it was originally in HEIF or HEVC format – choose Most Compatible.
4. Click download.

Check the network connection, see the following Apple articles:

Check the status of your network on Mac

Check the status of your network on Mac - Apple Support

You need to have a good Wi-Fi.

If they are On, turn Off Hotspot & VPN.

Charge the battery > 70%.

Turn Off VPN, see -> Change VPN settings on Mac

Change VPN settings on Mac – Apple Support (UK)

Make sure you don't have a firewall enabled: Change Firewall settings on Mac – Apple Support (UK)

If your Mac isn't connecting to the internet over Wi-Fi

If your Mac isn't connecting to the internet over Wi-Fi - Apple Support