When things like newsworthy events happen, it seems like often someone gets a long video of it on his or her phone. How do you do this? If I tried that on my phone (iPhone 6S) it would probably run out of memory in under a minute.
By “memory” do you mean storage space? You can adjust the settings on your camera to set how big the videos going to be. But if you can only take a minute long video you probably have filled up the storage you already have. Then again, an iPhone 6s is also a 6 year old phone.
I just checked my Galaxy S20. At 60 FPS, Full HD, I can take a 16 minute long video.
I can set my Android phone to record video on a Micro SD card. That gives me 20 minutes per gigabyte of time (recording at 720P). A 32 GB card can potentially hold 10 hours of continuous video, depending on settings.
At the highest setting on an iPhone 6, a minute of video takes up 400 MB. At the default setting (1080p, 60 fps), it’s 60MB, so you should be able to videotape quite a lot, depending on your storage space. A few minutes ain’t nothin’.
Well, not literally. Video had been recorded on tapes for so long that it seems to be the default to say that video is “taped” rather than “recorded” in many people’s vocabulary.
Hah. I started with “filmed” then went to “taped” and was just brain-farting at “recorded.” 
Don’t forget it’s possible to record to cloud storage, in which case you’re only limited to however much space the server has. Supposedly Google has a way to record directly to Google Drive but I’ve never experimented with it.
Can you put one in an iPhone 6S?
No idea how much storage I have, but I’ve been warned when I had a reasonable number of pictures and some music.
How do I do that on an iPhone 6S?
Settings > General > iPhone Storage
And, no, iPhones don’t take any external storage cards natively. There may be some kind of third-party adapter if you don’t mind a dongle hanging off your phone (I don’t know if there is or isn’t for a 6.)
No.The iPhones don’t have a card slot. You CAN get a external flash drive such as the Sandisk here.
I don’t know if it’s possible to tell the phone to record to that, though. You would need to verify that.
It looks like you can.
Shoot videos directly onto the iXpand Drive, freeing up space on your iPhone (Video first records to internal iPhone storage before automatically moving to iXpand Drive)
You need an app that does it. Though your phone is pretty old; you have a 6 and the latest iPhone is the 12 so that might be an issue.
Camra was a free app that did that but I can’t find it anymore. I’m having trouble finding a current app for iOS with the same feature.
Honestly though, your best bet is to get a better phone. My iPhone has 256GB of storage built in. I could record some really long videos if I wanted.
Have you actually tried it on your phone? You may be pleasantly surprised. I have a number of longish (news story length) videos on my phone (iPhone 8) with no storage issues.
At the highest setting (4K at 60fps) my iPhone 12 Pro uses 440mb per minute. With the amount of free space currently on my phone I could record almost 5 hours of video at the highest setting. And my phone is half full.
At the default setting of 1080p at 30fps, it only takes 65MB per minute. That means that right now I could record 32 hours of video.
I think you need a better phone.
More field data, a 1 minute video at 1920x1080 resolution of me panning back and forth across my desk was 156 megabytes. My phone has 86GB free, so that would be 551 minutes worth of video, so about 9 hours.
LOL.
I recorded a 2-hour video of the 2017 eclipse on an iPhone 4s.
You are either completely out of storage, or you are just guessing as to the longest video you can record.
Through trial and error I found that around 2 megabytes per second is the lowest I can go in h.265 at 1920x1080 before there is visible macroblocking in movement. But if I recode that video later (again in h.265) I can get the file 5 or 10 times smaller. The issue is that the best compression is hugely computationally intensive and can’t be done in real-time on a phone (at least none I’ve ever had.) But the codec does have the potential for compression that good if the hardware ever has the speed to match it.
Adding, at 2 MB/sec, and if your phone supports and can record to it, a 1 TB Micro SD card can hold 23 days of video.
My phone says ‘12.7 GB of 16 GB Used’.
In theory, that should be about 45 minutes of video at default setting. (3 GB/ 65 MB/min).
Also, before I wrote:
At the default setting (1080p, 60 fps), it’s 60MB,
That should be at 30 fps, not 60 fps. 60MB per min is the number Apple reports on my phone, but I used the more conservative number of 65MB mentioned by another poster above. If you go with 60MB, you get about 50 minutes of recording time for 3 GB.