from typing import Optional
import re


def parse_banner_timestamp(s: str) -> Optional[float]:
    """Get timestamp of rotation ad banner from an embedded script.
    The timestamp is rounded to seconds.
    """
    found = re.search(r"&times=(\d+)", s)
    if not found:
        return None
    timestamp_ns = float(found.group(1))
    return round(timestamp_ns / 1000, 0)