how to add one more data.channelTitle like data.title

computed: {
  filteredVideo() {
   return this.videos.filter(data => {
    return data.title.toLowerCase().includes(this.search.toLowerCase())
  })
}},

Like this:
https://codepen.io/AndrewThian/pen/QdeOVa

>Solution :

The question is vague so I assume you want to filter the list on basis of data.title as well as data.channelTitle as well. If that’s the case then,
add

data.title.toLowerCase().includes(this.search.toLowerCase()) || 
    data.channelTtile.toLowerCase().includes(this.search.toLowerCase())

This will filter out only if both the conditions(data.title and data.channelTtile) fail to match with this.search.