If you have already searched for or downloaded an unverified APK, take immediate steps to secure your phone:

: These files do not undergo the strict security screenings required by official app marketplaces. Major Risks of Installing Third-Party APKs

When a video application reaches a file size exceeding 500 MB, its architecture shifts from a simple streaming client to an self-contained environment.

This usually means you have an older version of the same app installed, or your device lacks the storage space required to unpack a 508 MB file. Free up at least 1.5 GB of internal space and try again.