CefSharpでH264を有効化したい

CefSharpを使ってブラウザを作っているのですが、Twitterの動画が再生されず以下のようになってしまいます

Xaml
1<Window x:Class="Browser.MainWindow"
2        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
3        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
4        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
5        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
6        xmlns:cef="clr-namespace:CefSharp.Wpf;assembly=CefSharp.Wpf"
7        xmlns:local="clr-namespace:Browser"
8        mc:Ignorable="d"
9        Title="MainWindow" Height="600" Width="820" Closing="Window_Closing" MinWidth="600" MinHeight="800" Loaded="Window_Loaded" KeyDown="Window_KeyDown" >
10                <Grid>
11                    <cef:ChromiumWebBrowser x:Name="browser" Grid.ColumnSpan="2"/>
12                </Grid>
13</Window>

C#
1namespace Browser
2{
3    /// <summary>
4    /// MainWindow.xaml の相互作用ロジック
5    /// </summary>
6    public partial class MainWindow : Window
7    {
8        public MainWindow()
9        {
10            InitializeComponent();
11            browser.Address = @"https://twitter.com/CatNaviDesk/status/847368727016259584/";
12            browser.BrowserSettings.Javascript = CefState.Enabled;
13            browser.BrowserSettings.JavascriptDomPaste = CefState.Enabled;
14            browser.BrowserSettings.LocalStorage = CefState.Enabled;
15            browser.BrowserSettings.DefaultFontSize = 16;
16            browser.BrowserSettings.BackgroundColor = 0x00FFFFFF;
17            browser.KeyboardHandler = new Handlers.KeyboardHandler();
18            browser.RequestHandler = new Handlers.RequestHandler();
19            browser.DisplayHandler = new Handlers.DisplayHandler();
20            browser.LifeSpanHandler = new Handlers.LifespanHandler();
21            browser.PreviewMouseWheel += CefBrowser_PreviewMouseWheel;
22            browser.KeyUp += CefBrowser_KeyUp;
23            browser.TitleChanged += CefBrowser_TitleChanged;
24        }
25    }
26}