If you're using the screenshot config for the Share button, then a long press will take you to the Share menu.
I use this same config and sometimes mine will take an extra screenshot or two when trying to get in there.
I'm not sure if it's just some jitter on the button itself, or if the firmware is flaky when it comes to interpreting the Share button press, or whatever else could be wrong with it, but the behaviour you describe lines up with my own experience.
Acutally you can; my brother is doing it with a friend, but it's tricky. It's like buying plus, having your account on both devices and interchanging devices with someone else.
Take: Skynet (my brother's PS4), and Cerebro (his friend's); Charlie (my brother's account) and David (his friend's).
There's an option in the PS4 that says something like: "Activate Device" for "Game" and for "Video", to activate a main account on the device.
David has Plus privileges on his account but his 'Active Device' is Skynet, and vice- versa Charlie has Cerebro as his main device. And they both have their accounts on both devices (main and secondary).
So on Cerebro are both accounts, Charlie and David. Charlie is the main account of that device but it's on David's house; and on Skynet too are both accounts, David is the main account, and it's in Charlie's house.
Basically David+ is playing with his account on Charlie's device, in his own house (as if he were a guest in his own device), and Charlie is playing in his house, with his account on David+'s, device.
Cerebro (in David+'s house): Skynet (in Charlie's house):
> -Charlie (Main) -David+ (Main)
> -David+ (2nd) -Charlie (2nd)
This way David+ can play online on Cerebro and on Skynet, because his account has plus, and Charlie can only play online on skynet because the main account of the device has plus and enables all accounts of the device to enjoy the plus privilege of online play.
And yes: anyone of them can buy a game and download/play them on both devices.
Best Answer
You can set how much the PS4 will record in advance by doing the following:
Press SHARE, press OPTION, then select "Length of Video Clip". You can set the following lengths:
Unfortunately, these values must be set before you choose to share a video. In other words, if you choose "1 Minute" and realize that the cool part started 2 minutes ago, that part will be lost by the time you press SHARE. Because of this, I'd recommend leaving this at "15 Minutes" (or setting it to that value) and instead go for the alternative.
Once the video is recorded, you can easily cut whatever it is you need using any video editing tool. Luckily, the PS4 has an official one made specifically for it, called SHAREfactory. You'll have to download it first, as it is not installed by default (at least not in the day-zero PS4s, as SHAREfactory wasn't available until several months after the PS4 launched). Its usage is relatively straightforward, so I won't explain it here.
Once you're satisfied with your work, press OPTION and select "EXPORT TO GALLERY". You might notice an option called "SAVE PROJECT". Since SHAREfactory doesn't modify video files, saving the project won't give you the video you're expecting. To get the video, you need to export it instead. Exporting takes time, so be patient.
You still might want to save the project, though, as you might encounter a situation where you might want to further modify your video by cutting even more content, or restoring already cut parts. Just remember to export the project once you're done, so your PS4 can create the requested (edited) video file.