subtitle-downloader/Program.cs

using OpenQA.Selenium;  
using OpenQA.Selenium.Firefox;  

public class Program {
    static void Main(string[] args) {

        Console.WriteLine("Starting");

        IWebDriver driver = new FirefoxDriver();

        // Base url: https://downsub.com/?url=https%253A%252F%252Fwww.youtube.com%252Fwatch%253Fv%253D
        // Finished url: https://downsub.com/?url=https%253A%252F%252Fwww.youtube.com%252Fwatch%253Fv%253D + video id
        string[] lines = File.ReadAllLines(@"/nfs/andre/Archive/Vtuber/Hologra/hologra_downloaded.txt");
        foreach (string line in lines) {
            string videoId = line.Substring(8, 11);
            string fullUrl = "https://downsub.com/?url=https%253A%252F%252Fwww.youtube.com%252Fwatch%253Fv%253D" + videoId;

            driver.Navigate().GoToUrl(fullUrl);
            Thread.Sleep(5000);

            IWebElement drop = driver.FindElement(By.XPath("//button[@class='v-expansion-panel-header px-4 py-2']")); // Open Dropdown [WORKS]
            drop.SendKeys(Keys.Enter);
            Thread.Sleep(1000);

            IWebElement check = driver.FindElement(By.Id("input-885")); // Click button to disable tag stripping [WORKS]
            check.SendKeys(Keys.Space);
            Thread.Sleep(1000);

            IWebElement sub = driver.FindElement(By.XPath("//button[@data-title='[SRT] English']")); // Download subtitle file [WORKS]
            sub.Click();
            Thread.Sleep(3000);

            driver.Close();

        }

        Console.WriteLine("Ended");
    }
}