delete_all_mp4.sh

#!/usr/bin/env bash
# Walk each immediate subfolder of this directory (e.g. sheep/, zebra/) and
# delete every .mp4 file found inside (recursively).
set -euo pipefail

BASE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
DELETE=0
if [[ "${1:-}" == "--delete" ]]; then
  DELETE=1
fi

find_mp4() {
  find "$1" -type f -iname '*.mp4' -print0
}

for dir in "$BASE"/*/; do
  [[ -d "$dir" ]] || continue
  name="$(basename "$dir")"
  [[ "$name" == ".cache" ]] && continue

  while IFS= read -r -d '' f; do
    if [[ "$DELETE" -eq 1 ]]; then
      rm -f -- "$f"
      echo "removed $f"
    else
      echo "$f"
    fi
  done < <(find_mp4 "$dir")
done

if [[ "$DELETE" -eq 0 ]]; then
  echo "Dry run only. Run with: $0 --delete" >&2
fi