can home theatre player support playing hd movie straight from external hdd?

hi... i'm new to to this topic... recently thinking about setting a home theatre system... i hav tonnes of hd movies inside my 2.5" external hdd which runs on usb connection.... most of my movies are in .mkv formats...

i would like to know if most home theatre player nowadays can play hd movies straight from external hdd? wouldnt it be laggy depending on the transfer rate?

thanks...