If you haven't done it already, you'll need to mash a video with the "Mash" button at the bottom of the main screen. [Here's a tutorial on how to mash a 1SE video.]
OK. Now you have this beautiful video and you want to share it. When you mash a video you'll see a "Save & Share" button at the bottom, tap it and in the next screen select the "Share" option. If you'd like to wait until later, no problem. You can go into your Photos app on your phone and find the 1SE album. Inside that album will be your mashed 1SE videos which you can share, delete, or view!
But I don't want to share it publicly 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.