The only condition for free use is a credit line. Personal YouTube videos and streams are free even if monetized (promoting a company or paid client work needs a license).
A dolphin call sound effect. Unrelated to the dolphin call itself, but it's surprising that dolphins and whales aren't actually distinct in biological classification — despite looking so different in size and shape.
If you're looking for whale call sound effects, check out Marine Animal Call – Whale 01 (Mammal) and Marine Animal Call – Whale 02 (Mammal).
