make sure to chmod +x it and should just work (provided you have curl and extended grep support)
#!/usr/bin/env bash
FILENAME="$1"
GIPHY_CODE_OR_URL="$2"
if [ -z "$FILENAME" ] || [ -z "$2" ]; then
echo "usage: $0 GIF_NAME GIPHY_URL_OR_CODE"
exit 1
fi
CODE_FROM_URL=$(echo "$GIPHY_CODE_OR_URL" | egrep -o 'media\/([A-Za-z0-9]{12,})\/giphy' | cut -d '/' -f 2)
if [ -z "$CODE_FROM_URL" ]; then
CODE_FROM_URL=$(echo "$GIPHY_CODE_OR_URL" | egrep -o '[A-Za-z0-9]{12,}')
fi
echo "saving to: $FILENAME.mp4"
echo "dling gif from: $GIPHY_CODE_OR_URL"
echo "giphy code: $CODE_FROM_URL"
curl "https://media.giphy.com/media/$CODE_FROM_URL/giphy.mp4" --output "$FILENAME.mp4"
xdg-open "$FILENAME.mp4" || true