You copy a video from your iPhone to your Windows PC, double-click it, and get "This item was encoded in a format that's not supported" (error 0xc00d5212), or sound over a black window. The same file plays perfectly on the iPhone, an iPad or a Mac. The cause is one specific thing: the video format the iPhone records in.
#The real problem: HEVC
Since 2017, iPhones have recorded video in HEVC (also called H.265) by default - that's what the "High Efficiency" option under Settings → Camera → Formats means. HEVC makes files about 40% smaller than the older H.264 at the same quality, but it's covered by patent royalties, and Microsoft doesn't include a decoder for it in Windows. That's true of Windows 11 as well as Windows 10: a fresh copy of either can't play HEVC. Many PCs come with a free decoder preinstalled by the manufacturer, which is why your iPhone videos might play on a friend's laptop and not on yours.
#What about the .mov file type?
It's a common assumption that Windows can't open .mov files, and that converting to .mp4 is the fix. Neither is true. Windows Media Player has played standard .mov files since Windows 7, and the current Media Player and Movies & TV apps play them too - MOV and MP4 are built on the same underlying format. Changing the file type from .mov to .mp4, whether by renaming it or by converting it without re-encoding, still leaves HEVC video inside, so Windows still can't play it.
#Four ways to fix it
1. Install HEVC Video Extensions ($0.99)
This is Microsoft's official decoder, from the Microsoft Store, for a one-time $0.99. Check first whether you already have the free manufacturer version: Settings → Apps → Installed apps, then search for "HEVC". Once it's installed, iPhone videos play in Photos, Media Player and Movies & TV, File Explorer shows their thumbnails, and - together with the free HEIF Image Extensions - .heic photos open too. HEVC Video Extensions explained covers whether it's worth it, and why the free version is no longer a reliable option.
2. Use VLC (free)
VLC brings its own HEVC decoder, so it plays iPhone videos on any Windows PC without any extension. It's the quickest fix if you only need to watch them. It doesn't help the Photos app, thumbnails, or anyone you send the file to.
3. Let the iPhone convert videos as you copy them
If you copy videos to the PC with a USB cable, the iPhone can convert them on the way. In Settings → Photos (Settings → Apps → Photos on iOS 18 and later), set Transfer to Mac or PC to Automatic: videos arrive as H.264 and .heic photos as JPEG. Keep Originals copies them as HEVC. This only applies to cable transfers - videos you get through iCloud, email or cloud storage stay HEVC.
4. Convert to H.264
For videos you're sending to other people, H.264 avoids the problem completely. It's about 40% bigger than HEVC but plays on every Windows PC, browser, phone and TV with nothing installed. Wave does this in your browser: drop the video, turn on Make it play everywhere, and it re-encodes the HEVC to H.264 without uploading anything - and converts HDR clips to standard colours on the way, so they don't look washed out. How long it takes depends on the clip. An SDR video is usually decoded by your computer's graphics chip and converts quickly; an HDR one - the iPhone default - goes through Wave's built-in engine, which takes a couple of minutes for 30 seconds of 1080p. For long HDR videos, HandBrake (free) on the desktop, with its "Fast 1080p30" preset, is quicker.
#Stop it happening: record in H.264
Settings → Camera → Formats → Most Compatible makes the iPhone record H.264 instead. Files are about 40% bigger, and some modes need High Efficiency: 4K at 60 frames per second, 240 fps slow motion, and HDR video. If you regularly hand videos to Windows users, it's worth switching. If not, keep High Efficiency and use one of the fixes above when you need to.
#Why isn't it simply built in?
HEVC's patents are held by many companies across several licensing pools, and every decoder shipped carries royalties. Apple pays them for iPhones and Macs. Microsoft has chosen not to pay them for every copy of Windows and sells the decoder separately instead - which is why the official fix costs 99 cents rather than nothing.
#The takeaway
iPhone videos won't play on Windows because they're recorded in HEVC, and neither Windows 10 nor Windows 11 includes an HEVC decoder unless your PC maker added one. The .mov file type isn't the problem, so renaming or rewrapping the file won't help. Install the $0.99 HEVC Video Extensions, watch in VLC, let the iPhone convert videos when you copy them over a cable, or convert to H.264 for anything you send to other people.