So, now you have this beautiful video and you want to share it! When you mash a video you'll be able to go into your reels sections and share that new video. To get to the reels section simply go back to the mashing screen and then tap the reels icon on the right-hand side. You can also go into your gallery app and look in the 1SE folder there.
But I don't want to share it publically and it's too big to email! HELP.
If you don't want to share it on social networks you can use a service like Dropbox, Google Drive, or a website like Wetransfer. These will allow you to upload the videos to the cloud, then send a link to someone or yourself. This will keep the video files from being compressed or run into any size limits with email clients.
One other option is to use Airdrop if you're trying to send it to your laptop or someone close by. This uses Bluetooth technology and can send files super quick.
TIP: Be mindful, mashed videos can take up a lot of space. If you're tight on storage, it's best to delete a mashed video once you've shared it or moved it to another device.