$def with ()

$ youtube_url = f"https://youtube.com/embed/"
<iframe id=youtubePlayer src=$:(youtube_url)BAdLRRbzOv4 type=text/html width=640 height=360 frameborder=0></iframe>
<label>Video: <input id=youtubeVideo></label>
<button id=youtubeChanger>Change</button>

$ twitch_url = f"https://player.twitch.tv/?parent={tx.host.name}&channel="
<iframe id=twitchPlayer src=$:(twitch_url)djmissshelton width=640 height=360 allowfullscreen></iframe>
<label>Channel: <input id=twitchChannel></label>
<button id=twitchChanger>Change</button>

<script type=module>
youtubeChanger.addEventListener('click', e => {
  youtubePlayer.src = `$:(youtube_url)$${youtubeVideo.value}`
})
twitchChanger.addEventListener('click', e => {
  twitchPlayer.src = `$:(twitch_url)$${twitchChannel.value}`
})
</script>