Game pictured: Castlevania Overflow Darkness
This can save up to 2.5 seconds total if done right, but some more routing may be necessary since the skip also bypasses 3 heart pickups. This skip itself saves 3.5 seconds but another damage boost earlier in the level that saves 1 second gets cut since there isn't room to take 4 hits, even in level 2.
levelengine presently has 13,768 views for Super Mario Bros. across 26 videos, with his channel uploading 4 hours worth of Super Mario Bros. videos. This is less than 0.12% of the total video content that levelengine has uploaded to YouTube.