With a USB 3.0 card reader, CrystalDiskMark shows blazing fast 47MB/s read but disappointingly slow 13MB/s write speed. So you can pretty much forget about reliable 1080P video recording.Update: It is correct that write speed great than 10MB/s is enough for 1080P recording. I need to clarify that the card is very slow when UHS-1 is not enabled. The read/write speeds drop to 13.3/7.9 MB/s. For devices that are a few years old such as Canon T2i which does not support UHS, 1080P recording may not be reliable. This card is classified as "class 10," it should support sustained write speed of at least 10MB/s without UHS. It fails my test, as observed by other reviewers as well.