Canon video recording stopped automatically problem but new question not like the other ones!
Typically the problem likely isn't the SD card speed. Depending on the camera it's likely limited because of file size or import taxation.

Most cameras use FAT32 as the file system on the SD card, which caps you out at 4GiB, so when you record enough footage to slam into that ceiling the camera will stop. Based on the Canon 6D we have in the office you can do ~10-15 minutes (depending on motion) at 1080p24 IPB mode, or 3-5 minutes 
in All-I mode.

Some cameras work around this by using AVCHD, which allows for longer clips to be spanned across multiple files (DVDs and the GoPro use a similar trick) but because AVCHD is an established system and specification it does constrain the formats and bitrates that can be recorded at (e.g. Canon's All-I mode can hit 70+MbPS but AVCHD tops out at about 28MbPS), and it uses MPEG-TS to store video which is a bit less intuitive than classic MP4/MOV files.

Other cameras work around this by using exFAT for the SD card file system, which allows for files greater than 4GiB, and can be read and written by both Windows and OS X. However Linux support is a bit spottier.

Now the ultimate question: why don't all cameras use one or both of these systems? The answer: money. exFAT needs to be licensed from Microsoft, and AVCHD from the AVCHD consortium (Panasonic and Sony; hence why those cameras most frequently feature AVCHD modes).

Then there's import taxation. Some countries classify any device that can record for 20 minutes or longer a "video camera," and thus are taxed differently on import. So some camera manufacturers will just stick with FAT32 to save money on both licensing and import tax, as it naturally restricts record time at higher resolutions, with recording limits imposed in software at lower resolutions.