image field

What do you mean with "grab a image / video"?

What is your use case? What do you want to achieve? What did you try? What failed? Any code snippets?

codeblog.jonskeet.uk/.../

For image field : https://docs.appian.com/suite/help/22.1/Image_Component.html,

For video field : https://docs.appian.com/suite/help/22.1/Video_Component.html

hope these two link will help you.

I think it can't be done.  What you could possibly do is achieve something with a document upload (given that a document can be virtually any kind of file), then using Image or Video component quite separately to display it once it's been uploaded.

You'll likely want to go through a bit of PM that chains to another form, or clever use of refresh variables and showWhen to get it to display roughly how you want.  Remember that uploading a thing and having it become a permanently stored document in Appian is a process.