link button property to open in new tab?

 By Adding following onClientClick even in your link button we can open the url in new tab.

OnClientClick="aspnetForm.target ='_blank';"

so on click it will call Javascript function an will open respective link in News tab.

<asp:LinkButton id="lbnkVidTtile1" OnClientClick="aspnetForm.target ='_blank';" runat="Server" Text="New Tab"  />

and another option is you can go for Hyper link control to achieve this. By default it has the Target property and you can set that to _blank.

thank you,