テキストファイルからまとめてVideosを設定するやつ。VRC_SyncVideoStream コンポーネントを右クリック。

VRC_PlaylistGenerator.cs

/**
 * VRC Playlist Generator
 *
 * Author: esnya
 * License: MIT License
 */

#if UNITY_EDITOR
using System.Linq;
using UnityEngine;
using UnityEditor;
using VRCSDK2;

public class PlaylistGenerator : EditorWindow
{
    [MenuItem("CONTEXT/VRC_SyncVideoStream/Load list of URLs from text")]
    static public void FromMenu(MenuCommand menuCommand)
    {
        var window = EditorWindow.GetWindow(typeof(PlaylistGenerator)) as PlaylistGenerator;
        window.videoStream = menuCommand.context as VRC_SyncVideoStream;
    }

    TextAsset urls;
    VRC_SyncVideoStream videoStream;

    void OnGUI()
    {
        urls = EditorGUILayout.ObjectField("URLs (\\n spritted text)", urls, typeof(TextAsset), false) as TextAsset;
        videoStream = EditorGUILayout.ObjectField("VRC_SyncVideoStream", videoStream, typeof(TextAsset), false) as VRC_SyncVideoStream;
        var valid = urls != null && videoStream != null;

        EditorGUI.BeginDisabledGroup(!valid);
        if (GUILayout.Button("Generate")) {
            videoStream.Videos = urls.text.Trim().Split('\n').Select(line => {
                var entry = new VRC_SyncVideoStream.VideoEntry();
                entry.URL = line.Trim();
                return entry;
            }).ToArray();
        }
        EditorGUI.EndDisabledGroup();
    }
}
#endif

yt-playlist-to-url-list.js

// YouTubeのプレイリスト画面でコンソールに入れるとなにかできるかもしれない
console.log(Array.from(document.querySelectorAll('ytd-playlist-video-renderer.style-scope > div:nth-child(2) > a:nth-child(1)')).map(a => a.href.replace(/&.*$/, 'g')).join('\n'));