WhatsApp sends up to 12MB so that’s out. Gmail sends only 30MB tops, and the new feature to use Google Drive to send files still does not have a direct download feature, so you can only stream the video from your Google Drive. And Grandpa doesn’t know how to do this from his mobile because the Google Drive “send file” feature is not available on mobile and asking grandpa to use a PC would necessitate you heading down to his condo to do tech support. Dropbox needs your dad to install dropbox on his Android phone and it’s not easy.