The replay buffer normally sits in RAM, but you can dump it to a file too. Would that give you the snippets you need?
I couldn't find the command in OBS natively, but the Advanced Scene Switcher plugin can do it, as shown here.
This plugin will allow you to automate various tasks using "Macros". Macros consist of a list of conditions under which a list of actions will be performed. Examples and guides can be found in the wiki. Feel free to contribute! If you run...
obsproject.com
If you use the hotkey method as shown, then the name that you give it appears in OBS's normal list of hotkeys, and you can assign the actual key from there.