The term "extra quality" on these sites is a marketing label for files that use advanced compression codecs (like x265 or HEVC) to maintain watchable visual quality at very small file sizes.
These codecs allow for "10-bit" video, which provides better color depth and smoother gradients even at lower bitrates.
Standard HD streaming can consume up to 3GB per hour.
Many of the redirect links used by these sites can lead to phishing pages designed to steal personal information. Legitimate Alternatives