Basically what Google has done in the latest Google Photos is that when you upload a video to Google Photos, a low-res copy will be uploaded first, meaning that if the video is so important that the other person can’t wait for a hi-res copy, not to worry as the low-res copy will be uploaded and made available for viewing right away.
As Google points out, users don’t have to worry as it will be later replaced by a high-resolution copy (this will depend on the quality you recorded it in in the first place). “We’ve reduced the wait time for sharing videos in Google Photos by uploading low-res copies for sharing, and later replacing them with the high-res versions.”
The latest update to Google Photos is already available so if you haven’t updated the app already, head on over to the Google Play Store for the download. Note that the update is only available for Android right now so iOS users will have to wait their turn.