When tapping a picture or video, the multimedia gallery will open. From there, you can access all the conversation’s multimedia files. Pictures and videos, both sent and received, will be available there and can all be played.
You can also delete pictures and videos by tapping the trash bin icon. When doing so, you will have the option of deleting the file from the gallery or deleting it from the conversation as well. If you only delete it from the gallery, you can always download the file again.
Also, when opening a file from the conversation, you can share it with other apps by tapping the share icon on the bottom right corner.