The download time depends on the size of the movie and the Internet speed, but it usually takes about four times the movie length for the download to finish. For example, a 2-hour movie will take around eight hours for the download to finish if the Internet speed averages 10Mbps.
The 4K PlayStation Video (formerly known as 4K Video Unlimited) Store, however, is designed to minimize the time it takes to download movies. One feature of the store is the Auto Download of new titles to the 4K media player each month.
NOTE: If the Auto Download feature causes you to exceed your monthly bandwidth limit, turn off the setting which can be found in the Settings menu of the 4K media player.