Most of the video links available in this platform, can be used regularly by just pasting its URL on the slide, using a Video content block. However, when using custom videos that you have uploaded yourself to Vimeo, you'll need to use its standard URL instead of the custom one.
To find it, go into the Advanced Settings of your video and temporarily empty the custom URL field. The Preview link, shown below the empty Custom URL field, is the one to be pasted on your slide. This is how the setting looks:
