Exactly what MadCatX said. I have 2 screens and that isn't a problem. As soon as the LFS window loses focus you lose sound. So during the broadcast you can't use an external program for overlays without your sound cutting in and out everytime you click.
I suppose it would be possible to make DirectSound think that LFS wants its sound buffers to be treated as global, which is exactly what would do the trick. If there's enough demand for it, it might look into ways how to accomplish this.
I use to use procaster with livestream and got the best display with it. However they have done some renovations lately that I don't find too appealing. I had an account there since 2006 and was "grandfathered in" to having no stream cap limit, so it was quite nice.
Now however I have been using XSplit. I help broadcast for an iRacing company and they utilize Twitch and own3d currently. I also do other iRacing broadcasts that most of the time is on one of my Livestream accounts.
Finally on LFS I use my Livestream account. It's much more viewer friendly and I can make the page look pretty.
I found a silly way around it. Unfortunately I need my laptop for TV Director, but for overlays I have to use my phone, yes, my phone.
I'm using an app called gPad for Android. I link my PC and phone through WiFi and then can use my phone to control my PC. Not like remote access. I can use the app as a mouse, or I can use it to my "buttons" which are basically just button combos or scripts.
So then I create a new sheet and place buttons that are for each scene and overlay. It's a lot of work and jumping from PC to laptop to phone is definitely not ideal for a broadcast. iRacing for example has the sound option so I run everything on my PC, while is so much easier it is unreal.
There is another app (for Android phones) similar to gPad that I think may be more powerful, flexible and easier for programming the buttons it is called Unified Remote. I have not played enough with it but it uses XML (PC-side) to define the button layouts on the phone.
Well unfortunately there isn't an automatic overlay system like with the iRTVO tool made for iRacing. Instead you have to do the overlays manually using XSplit and its scenes. Currently the main stuff to overlay would be race information, previous results and points, qualifying for the race, and a display showing who the commentators are.
Obviously it is unavailable to show drivers and teams through overlays currently. TV director already has a small system for that anyways. The thing is, its overlay is by insim buttons I believe, where as it would be much easier to have the data extracted and easily configurable to display on images we create.
It would look a lot more professional and much much easier as a whole package.
Older versions of LFS used waveOut whereas current versions use DirectSound, because waveOut didn't work correctly on Vista. DirectSound has to be specifically told to use global sound buffers so you could hear the sound even when application is backgrounded.
I just tested it on Vista in windowed mode, and after I actually got the sound to work by putting sound lag up to 0.24, I drove about then watched the replay - clicked off LFS and I still had the sound!
I don't want to be offensive, but Vista is the most bullshit Operating system ever.
Almost anyone with 5.1 surround and Vista has problem. Heck, even Bill Gates himself said Vista sucked. (google it)
As an apology for Vista, they released Windows 7, a bit better....
You don't want issues? Use windows XP or Mac....
(everyone has an XP cd-key or they aren't hard to get for free, LEGALLY)