The growing popularity of online video has caught the attention of malicious hackers and hi-tech criminals.

Security firms are reporting more and more instances of booby-trapped Windows codecs - file compressors - required to play some video formats.

Some of the codecs let users play types of net-based video, but also have spyware and adware wrapped inside.

Others, say experts, are outright fakes that just want to infect victims with data-stealing programs.