The grammar of 'see' and 'hear' allows these constructions. These are called catenative verbs. You may want to use Google to find more information about catenative verbs.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
andybusy.....The first sentence has two main verbs "saw" and "come" but with no conjunction in between.The sentences can be revised to require a conjunction. But they become longer sentences.